B-25 Mitchell

1. Lead

The B-25 Mitchell was the most versatile medium bomber of the Second World War, and one of the most famous American aircraft of the war. Designed by North American Aviation and named after General Billy Mitchell, the advocate of air power, the B-25 was a twin-engine bomber that could do almost anything: it could bomb from medium altitude, it could strafe at low level with a nose full of machine guns, it could carry a 75 mm cannon, it could drop torpedoes, and it could take off from an aircraft carrier — as sixteen B-25s did on 18 April 1942, in the Doolittle Raid on Tokyo, the first American strike on the Japanese home islands. About 9,816 B-25s were built, and they served in every theatre of the war: in the Pacific, in the Mediterranean, in North Africa, in Europe and on the Eastern Front, where the Soviet Union received hundreds under Lend-Lease. The B-25 was fast, tough and easy to fly, and it remained in service after the war, in the air forces of many countries, into the 1960s. Today, restored B-25s are among the most popular warbirds at airshows, and the Doolittle Raid is still remembered as one of the great feats of American aviation.

2. Key Facts

Type	Medium bomber (later versions: ground-attack / strafer)
Origin	United States
Designer	North American Aviation (James H. Kindelberger; Lee Atwood)
Manufacturer	North American Aviation, Inglewood and Kansas City
First flight	19 August 1940
Introduced	1941
Produced	1941–1945; 9,816 built
Crew	5–6 (pilot, co-pilot, navigator/bombardier, radio operator, gunners)
Length	16.1 m (B-25J)
Wingspan	20.6 m
Height	4.8 m
Empty weight	About 9,580 kg (B-25J)
Maximum take-off weight	About 15,870 kg (B-25J)
Engines	2 × Wright R-2600-92 Double Cyclone radial, 1,700 hp each
Maximum speed	About 438 km/h (B-25J)
Range	About 2,170 km (with normal bomb load)
Service ceiling	About 7,600 m
Armament (B-25J)	Up to 12–18 × 12.7 mm (.50 cal) machine guns, depending on version
Bomb load	Up to about 1,360 kg internally (up to about 2,700 kg with external stores on some versions)
Named after	Major General William “Billy” Mitchell

3. Background and Development

The Requirement and the NA-40

The B-25 was born of the United States Army Air Corps’ requirement, issued in 1938, for a twin-engine medium bomber that could carry a bomb load of about 1,100 kg over a range of about 2,000 km at a speed of about 320 km/h. North American Aviation, which had never built a bomber before, answered with the NA-40, a twin-engine aircraft powered by two Pratt & Whitney R-1830 engines, which first flew in January 1939. The NA-40 was underpowered, and North American redesigned it as the NA-62, with more powerful Wright R-2600 engines, a larger wing and a revised fuselage. The NA-62 first flew on 19 August 1940, and it was ordered into production at once as the B-25, because the Army Air Corps needed bombers urgently and because the aircraft’s performance was better than the specification required. The B-25 was named after Major General William “Billy” Mitchell, who had been court-martialled in 1925 for his advocacy of air power and who had died in 1936, and it was the first American military aircraft to be named after a person.

The Doolittle Raid and the Decision to Build

The B-25’s fame was made by the Doolittle Raid, but its production was decided before the raid. In 1941, the Army Air Corps ordered the B-25 into mass production, and North American built two factories — at Inglewood, California, and at Kansas City, Missouri — to build it. The first B-25s entered service in 1941, and by the time of the Japanese attack on Pearl Harbor in December 1941, the Army Air Forces had about 100 B-25s in service. The Doolittle Raid, in April 1942, used sixteen B-25B bombers, which were launched from the aircraft carrier USS Hornet to bomb Tokyo and other Japanese cities. The raid did little physical damage, but it was a great propaganda victory: it showed that Japan was vulnerable to attack, and it raised American morale at a time when the United States had suffered nothing but defeats in the Pacific. The raid also made the B-25 famous, and production was increased to meet the demand for the aircraft in every theatre.

Mass Production

The B-25 was produced in large numbers, and its production was a triumph of American industrial organisation. North American built 9,816 B-25s between 1941 and 1945, in a series of versions from the B-25A to the B-25J, and the aircraft was also built in a training version, the AT-24, and in a transport version, the CB-25. The B-25J, which was the most-produced version, accounted for 4,318 aircraft, and it was built at both the Inglewood and the Kansas City plants. The B-25’s production was shared with the B-24 Liberator and the P-51 Mustang, which were also built by North American, and the company’s factories were among the most productive in the United States. The B-25 was also supplied to America’s allies under Lend-Lease: Britain received about 900, the Soviet Union received about 870, and smaller numbers went to Australia, Canada, China, France, the Netherlands and Brazil. The B-25’s production was also a triumph of logistics: the aircraft’s parts were made in factories all over the United States, and they were assembled at Inglewood and at Kansas City, where the production lines, at their peak, turned out a new B-25 every few hours.

4. Design

A Twin-Engine Medium Bomber

The B-25 was a conventional twin-engine medium bomber, with a mid-mounted wing, a twin tail and a tricycle landing gear — one of the first American bombers to use a nosewheel, which made it easier to take off and to land than the tail-draggers that preceded it. Its fuselage was a semi-monocoque structure of aluminium alloy, its wing was a two-spar structure with a dihedral, and its two Wright R-2600 Double Cyclone radial engines, each of 1,700 horsepower, gave it a top speed of about 438 km/h and a range of about 2,170 km. The B-25’s crew of five or six worked in a spacious fuselage, with the pilot and co-pilot in the cockpit, the navigator and bombardier in the nose, and the radio operator and gunners in the centre and rear of the aircraft. The aircraft’s bomb bay, in the centre of the fuselage, could carry up to about 1,360 kg of bombs, and the later versions could carry more on external racks.

The Gunship Versions

The B-25’s most distinctive design feature was its adaptability, and nowhere was this clearer than in the gunship versions. In the Pacific, in 1942–43, the Fifth Air Force, under General George Kenney, found that the B-25’s glazed nose, with its bombardier, was useless for the low-level attacks on Japanese shipping that were needed in New Guinea, and Kenney’s men replaced the bombardier’s position with a solid nose containing four, and later eight, .50-calibre machine guns, which fired forward and which could strafe a ship or an airfield at low level. The B-25G added a 75 mm cannon in the nose, which could fire a shell that could sink a ship, and the B-25H added four more machine guns and a lighter 75 mm cannon. The B-25J, the final version, could be built with either a glazed nose or a solid gun nose, and the gun-nose J could carry up to 18 .50-calibre machine guns — the heaviest forward firepower of any bomber of the war. The gunship B-25s were devastating against Japanese shipping, against airfields and against troops in the open, and they became the standard low-level attack aircraft of the Pacific war.

Toughness and Ease of Flying

The B-25 was known for its toughness and for its ease of flying. Its airframe was strong, its engines were reliable, and it could absorb a great deal of battle damage and still bring its crew home. The aircraft’s twin engines gave it a margin of safety: a B-25 could fly on one engine, and many crews brought their aircraft home on a single engine after the other had been shot away. The B-25 was also easy to fly, with light controls and good handling, and it was popular with its pilots, who regarded it as one of the best-handling bombers of the war. The aircraft’s only serious weakness was its defensive armament: the early versions had only a few machine guns, and they were vulnerable to fighter attack, but the later versions, with their powered turrets and their heavy nose armament, were better protected. The B-25’s toughness and its ease of flying are the reasons why it remained in service after the war, and why so many survive today.

5. Variants

The Main Production Versions

Variant	Years	Key features	Production
B-25A	1941	First production version; self-sealing fuel tanks	40
B-25B	1941–1942	Improved defensive armament; used in the Doolittle Raid	120
B-25C/D	1942–1943	Most-produced early version; R-2600-13 engines	About 3,800 (C and D combined)
B-25G	1942–1943	Solid nose with 75 mm cannon and 2 machine guns	463
B-25H	1943–1944	Lighter 75 mm cannon; 4 nose machine guns; more guns	1,000
B-25J	1943–1945	Most-produced version; glazed or solid nose; up to 18 machine guns	4,318
F-10	1943–1945	Photo-reconnaissance version of the B-25D	45
AT-24 / TB-25	1941–1945	Trainer versions	Several hundred

The B-25 was produced in a series of versions, each of which reflected the lessons of combat. The B-25A and B-25B were the first production versions, and they were used in the Doolittle Raid and in the early fighting in the Pacific. The B-25C and B-25D, which were built at Inglewood and Kansas City respectively, were the workhorses of 1942–43, and they were the versions that fought in North Africa, in the Mediterranean and in the Pacific. The B-25G and B-25H were the gunship versions, with a 75 mm cannon in the nose, and they were used for low-level attacks on shipping. The B-25J, which was the final and most-produced version, could be built with either a glazed bombardier’s nose or a solid gun nose, and it combined the lessons of all the earlier versions: it was fast, heavily armed and versatile, and it served in every theatre of the war.

The Gun Nose and the Glazed Nose

The B-25J’s two nose options — the glazed nose for level bombing and the solid gun nose for strafing — were the clearest expression of the aircraft’s versatility. The glazed nose, with its bombardier and its Norden bombsight, was used for medium-altitude bombing, where accuracy mattered, and the solid nose, with its eight .50-calibre machine guns, was used for low-level strafing, where firepower mattered. The two noses could be interchanged in the field, and squadrons often had both types, using the glazed-nose aircraft for bombing and the gun-nose aircraft for strafing. The gun-nose B-25J, with its 18 machine guns, was the most heavily armed bomber of the war, and its forward firepower was greater than that of any fighter. The B-25’s ability to be both a bomber and a gunship, in the same airframe, is the reason why it was so widely used, and why it remained in service for so long after the war.

6. Operational History

The Doolittle Raid, April 1942

The B-25’s most famous action was the Doolittle Raid of 18 April 1942, in which sixteen B-25B bombers, led by Lieutenant Colonel James H. Doolittle, took off from the aircraft carrier USS Hornet and bombed Tokyo, Yokohama, Yokosuka, Nagoya and Kobe. The raid was the first American air attack on the Japanese home islands, and it was a daring feat: the B-25 was not designed to take off from a carrier, and the bombers had to be stripped of weight, fitted with extra fuel tanks and flown by crews who had trained for only a few weeks. The bombers took off from the Hornet about 650 nautical miles from Japan — further than planned, because the task force had been detected by a Japanese picket boat — and they bombed their targets and then flew on to China, where most of the crews bailed out or crash-landed. Three men were killed in the raid, eight were captured by the Japanese, of whom three were executed, and the rest reached safety. The raid did little physical damage, but it was a great moral victory, and it forced the Japanese to keep fighters at home for the defence of the islands, which weakened their forces in the Pacific.

The Pacific, 1942–1945

In the Pacific, the B-25 was the workhorse of the Fifth Air Force in New Guinea and the Philippines, and of the Thirteenth Air Force in the Solomon Islands. The gunship B-25s, with their nose full of machine guns and their 75 mm cannon, were devastating against Japanese shipping in the Bismarck Sea, where in March 1943 American and Australian aircraft, including B-25s, destroyed a Japanese convoy and sank eight transports and four destroyers, killing about 3,000 Japanese soldiers. The B-25s also attacked Japanese airfields, Japanese troops and Japanese supply lines, and they flew in support of the American landings in New Guinea, in the Philippines and on Okinawa. The B-25’s ability to operate from rough, forward airfields, and to absorb battle damage, made it ideal for the Pacific war, and its crews flew hundreds of sorties against targets that were often only a few hundred metres from friendly troops.

The Mediterranean, North Africa and Europe

The B-25’s war was not only the Pacific War: the aircraft also served in the Mediterranean, in North Africa and in Europe, where it bombed German and Italian positions, attacked shipping and supported the Allied armies as they advanced up the Italian peninsula and into Germany. The two sections below describe the B-25’s service in the Mediterranean and in North Africa, and its service on the Eastern Front, where the Soviet Union received hundreds of B-25s under Lend-Lease, and in the final months of the war in Europe. The B-25’s service in these theatres was less famous than its service in the Pacific, but it was no less important, and it showed the aircraft’s versatility in every kind of warfare.

The B-25’s service in the Mediterranean was the work of the Twelfth Air Force, which was formed in 1942 to support the Allied landings in North Africa, and which flew B-25s in Tunisia, in Sicily and in Italy. The Twelfth Air Force’s B-25s bombed German and Italian positions, attacked shipping in the Mediterranean, and supported the Allied armies as they advanced up the Italian peninsula, in some of the hardest fighting of the war.

North Africa and the Mediterranean

In the Mediterranean, the B-25 served with the Twelfth Air Force in North Africa and Italy, and with the Royal Air Force, which received about 900 B-25s under Lend-Lease and used them as the Mitchell II and III. The B-25s bombed German and Italian positions in Tunisia, in Sicily and in Italy, and they attacked shipping in the Mediterranean, where their low-level attacks were effective against German supply convoys. The B-25’s service in the Mediterranean was less famous than its service in the Pacific, but it was no less important: the B-25s of the Twelfth Air Force flew thousands of sorties in support of the Allied advance up the Italian peninsula, and they bombed the German defences at Monte Cassino and at Anzio. The Royal Air Force’s Mitchells also served in the Far East, where they bombed Japanese positions in Burma, and in Europe, where they bombed German targets in France and the Low Countries.

The Eastern Front and the End of the War

The Soviet Union received about 870 B-25s under Lend-Lease, and they were used by the Soviet Air Force as medium bombers and as transports. The Soviet B-25s bombed German positions on the Eastern Front, and they were used in the final offensives of 1944–45, including the offensives that liberated Eastern Europe and that advanced on Berlin. The Soviet crews valued the B-25 for its toughness and for its ease of flying, and they regarded it as one of the best aircraft they received under Lend-Lease. In Europe, the B-25 also served with the Free French, the Dutch and the Brazilians, and it flew in the final months of the war in support of the Allied advance into Germany. The B-25’s last combat missions were flown in the Pacific, in the summer of 1945, against Japanese positions in the Philippines and on Okinawa, and the aircraft remained in service after the war, in the air forces of many countries, into the 1960s.

7. Performance and Specifications

Specifications

Specification	B-25J
Engines	2 × Wright R-2600-92, 1,700 hp each
Maximum speed	About 438 km/h
Cruising speed	About 370 km/h
Range	About 2,170 km
Service ceiling	About 7,600 m
Rate of climb	About 4 m/s (estimated)
Empty weight	About 9,580 kg
Maximum take-off weight	About 15,870 kg
Bomb load	Up to about 1,360 kg internally
Armament	Up to 12–18 × 12.7 mm machine guns
Crew	6
Number built	9,816 (all versions)

The table shows the B-25J, the most-produced version, and its performance was typical of a medium bomber of the period: fast enough to outrun most fighters at low level, with a range that allowed it to strike targets deep behind the front, and with a bomb load that was sufficient for the tactical bombing for which it was designed. The B-25’s maximum speed of about 438 km/h was about the same as that of the German Heinkel He 111 (about 440 km/h) and faster than that of the Japanese Mitsubishi G4M (about 430 km/h), and its range of about 2,170 km was greater than that of most medium bombers. The B-25’s greatest strength was not any single figure but its versatility: the same airframe could be a level bomber, a strafer, a torpedo bomber and a reconnaissance aircraft, and it could operate from a carrier, from a rough forward airfield and from a paved runway.

Comparison with Other Medium Bombers

Compared with the other medium bombers of the war, the B-25 was the most versatile and one of the fastest. The German Junkers Ju 88, which was the standard German medium bomber, was faster (about 470 km/h) and could carry a heavier bomb load, but it was more complex and more difficult to fly. The British Vickers Wellington, which was the standard British medium bomber in the early war, was slower (about 410 km/h) and less heavily armed, and it was withdrawn from front-line service earlier. The Japanese Mitsubishi G4M, which was the standard Japanese medium bomber, was faster and had a longer range, but it was lightly built and vulnerable to fire, and it was nicknamed the “flying lighter” by its crews. The American Martin B-26 Marauder, which was the B-25’s rival in the American inventory, was faster and could carry a heavier bomb load, but it was more difficult to fly and had a higher accident rate. The B-25’s balance of speed, range, bomb load, toughness and ease of flying made it the most successful medium bomber of the war, in the judgement of many historians.

8. Operators

The United States

The B-25 was used principally by the United States, and it served with the United States Army Air Forces in every theatre of the war. The B-25’s main users were the Fifth Air Force in the Pacific, the Twelfth Air Force in the Mediterranean, the Ninth Air Force in Europe and the Tenth Air Force in Burma, and the aircraft also served with the United States Marine Corps, which used it as the PBJ-1, a patrol bomber, in the Pacific. The B-25 remained in American service after the war, in the United States Air Force and in the Air National Guard, until the 1950s, and it was used as a trainer, as a transport and as a target tug. The B-25’s American service was the longest and the most extensive of any of its operators, and it is the American B-25 that is best remembered today, above all for the Doolittle Raid.

Allies and Post-War Users

The B-25 was supplied to America’s allies under Lend-Lease, and it was used by Britain, the Soviet Union, Australia, Canada, China, France, the Netherlands, Brazil and many other countries. Britain received about 900 B-25s and used them as the Mitchell II and III, in the Mediterranean, in the Far East and in Europe. The Soviet Union received about 870 B-25s and used them on the Eastern Front. Australia received about 50 B-25s and used them in the Pacific. After the war, the B-25 was used by the air forces of more than thirty countries, including Indonesia, which used it in its war of independence against the Netherlands, and the Dominican Republic, which used it into the 1960s. The B-25’s wide distribution is one reason why it is so well known today, and why restored B-25s can be seen at airshows around the world. The B-25’s post-war service was as wide as its wartime service: the aircraft was used by the air forces of more than thirty countries, and it remained in service in some of them into the 1960s, more than twenty years after the first B-25 flew.

9. Legacy and Influence

The Doolittle Raid

The B-25’s legacy is above all the Doolittle Raid, which is one of the most famous air operations in history. The raid, in which sixteen B-25s took off from an aircraft carrier to bomb Japan, is remembered as a feat of courage and of improvisation, and it is still studied by air forces around the world. The raid’s leader, James Doolittle, was awarded the Medal of Honor, and the raiders became national heroes in the United States. The Doolittle Raid also changed the course of the war: it forced the Japanese to keep fighters at home, it contributed to the Japanese decision to attack Midway, and it showed the world that the United States could strike back after Pearl Harbor. The B-25 is therefore remembered not only as an aircraft but as the aircraft of the Doolittle Raid, and the two are inseparable in the public imagination. The raiders’ reunions, which were held annually for more than seventy years, were a reminder of the raid’s place in American memory, and the last surviving raider, Lieutenant Colonel Richard Cole, died in 2019, at the age of 103.

The Versatile Medium Bomber

The B-25’s other legacy is its versatility, which became the model for the medium bomber. The B-25 showed that a medium bomber could be a level bomber, a strafer, a torpedo bomber and a reconnaissance aircraft, and that the same airframe could be adapted to many roles. The aircraft’s success influenced the design of post-war bombers, and its gunship versions influenced the design of the gunships of the Vietnam War, above all the AC-47 and the AC-130, which, like the B-25 gunships, were transport and bomber aircraft converted to carry heavy forward-firing armament for low-level attack. The B-25’s long service — from 1941 to the 1960s, in more than thirty air forces — is a measure of the soundness of its design, and of the versatility that North American built into it. Today, the B-25 is one of the most popular warbirds in the world, and its story is told in museums, in films and in the airshows where restored B-25s still fly.

10. Surviving Examples

Museums

About 40 B-25s survive today, in museums and in private collections, and many of them are in flying condition. The best-known museum examples include the B-25J at the National Museum of the United States Air Force in Dayton, Ohio, which is displayed as a Doolittle Raider, and the B-25 at the Smithsonian National Air and Space Museum in Washington, D.C. Other B-25s are held at the Imperial War Museum at Duxford in Britain, at the Australian War Memorial in Canberra, and at the museums of Canada, the Netherlands and Brazil. The B-25’s survival rate is high for a wartime bomber, because so many were built and because the aircraft remained in service after the war, and the surviving aircraft are among the most popular exhibits in the museums that hold them. The National Museum of the United States Air Force’s B-25J, which is displayed as a Doolittle Raider, is one of the museum’s most visited aircraft, and it is displayed with the story of the raid and with the names of the sixteen crews who flew it.

Flying Warbirds

A large number of B-25s still fly, and they are among the most popular warbirds at airshows in the United States and around the world. The Commemorative Air Force, the largest operator of flying warbirds, operates several B-25s, and other B-25s are flown by private owners and by museums. The flying B-25s appear at airshows, at commemorations of the Doolittle Raid and at flypasts, and they are often flown in formation with other warbirds, including the B-17 Flying Fortress and the P-51 Mustang. The Doolittle Raiders’ reunions, which were held annually until the last survivors died, were always attended by a flying B-25, and the aircraft’s presence at those reunions was a reminder of the raid and of the men who flew it. For most people, the easiest way to see a B-25 is at an airshow, where the sound of its two Wright engines is one of the most recognisable sounds in aviation.

Frequently Asked Questions

What is the B-25 Mitchell?
The B-25 Mitchell was an American twin-engine medium bomber of the Second World War, designed by North American Aviation and named after General Billy Mitchell. About 9,816 were built.

What was the Doolittle Raid?
The Doolittle Raid was an American air attack on Tokyo and other Japanese cities on 18 April 1942, in which sixteen B-25 bombers, led by Lieutenant Colonel James Doolittle, took off from the aircraft carrier USS Hornet to bomb Japan.

How many B-25s were built?
9,816 B-25s were built between 1941 and 1945. The most-produced version was the B-25J, with 4,318 built.

What was the B-25 gunship?
A version of the B-25 with a solid nose containing machine guns and, on the G and H versions, a 75 mm cannon, designed for low-level strafing attacks on shipping and airfields. The B-25J gun-nose version could carry up to 18 .50-calibre machine guns.

Who else flew the B-25?
Britain received about 900 B-25s, the Soviet Union about 870, and smaller numbers went to Australia, Canada, China, France, the Netherlands and Brazil, all under Lend-Lease.

Ai khác bay B-25?

Where can I see a B-25 today?
At the National Museum of the United States Air Force in Dayton, Ohio, the Smithsonian National Air and Space Museum in Washington, D.C., and the Imperial War Museum at Duxford, among other museums. Many B-25s still fly at airshows.

Sources

1. Wikipedia, “North American B-25 Mitchell” — production of 9,816, specifications, the Doolittle Raid.
2. National Museum of the United States Air Force, “North American B-25 Mitchell” — the Doolittle Raider on display at Dayton.
3. Smithsonian National Air and Space Museum, “North American B-25J Mitchell” — specifications and surviving aircraft.
4. Carroll V. Glines, The Doolittle Raid (Schiffer, 1991) — the raid of 18 April 1942.
5. William Wolf, The B-25 Mitchell in World War II (Schiffer, 2013) — variants, the gunship versions and operational history.
6. U.S. Naval History and Heritage Command, “Doolittle Raid” — the raid and the USS Hornet.