How the B-25 Mitchell Bomber Became a World War II Legend

How the B-25 Mitchell Bomber Became a World War II Legend

Nicknamed “Billy’s Bomber” and “The Sweetheart of the Services,” the Mitchell was beloved by pilots because of its ability to wreak havoc on enemy targets.

Here's What You Need to Know: The North American B-25 Mitchell medium bomber proved a versatile combat platform in all theaters.

Little more than four months after the disastrous attack on Pearl Harbor, America went on the offensive against Japan with one of the boldest and best remembered bomber raids of World War II. Led by Lt. Col. James H. “Jimmy” Doolittle and laden with extra fuel, 500-pound bombs, and incendiary clusters, 16 North American B-25 Mitchell bombers lumbered 500 feet along the wooden flight deck of the 19,900-ton Yorktown-class aircraft carrier USS Hornet (CV-8) early on Saturday, April 18, 1942, and took off into a stiff wind.  They climbed into a rainy, murky sky and flew 800 miles eastward to hit military targets in the Tokyo, Nagoya, Kobe, and Yokohama areas.

It was the first and only time that bombers had been launched from a carrier, and they achieved complete surprise when they reached their objectives. The material damage they inflicted was slight, but the raid had a major psychological impact.  The stunned Japanese were forced to push forward their planned attack on Midway Atoll, preventing further carrier attacks against their country, while the Americans received a much needed morale lift after a series of defeats in the Far East.

The gallant Doolittle was awarded the Medal of Honor, and his historic raid—the country’s first victory of the war—gained instant fame for the North American B-25 Mitchell, one of the most widely used and effective twin-engine bombers of the war. Meanwhile, the chunky, affable Doolittle, a record-breaking peacetime air racer, became a national hero and went on to command successively the U.S. Twelfth and Fifteenth Air Forces, the Northwest African Strategic Air Force, and the Eighth Air Force.

The B-25 “Mitchell” Bomber: Origin of the Name

Named for Brig. Gen. William “Billy” Mitchell, the charismatic airpower prophet who proved in 1921 and 1923 that planes could sink battleships, the B-25 Mitchell gained an unsurpassed reputation as a ground-attack bomber and ship killer. The rugged, versatile B-25 saw action on almost every Allied front, from the Mediterranean to the Pacific, and from Burma to Normandy, and was regarded by many as the most successful twin-engine combat aircraft of World War II.

The plane was conceived before the outbreak of the 1939-1945 war. In response to an Army Air Corps proposal for a twin-engine attack bomber, North American Aviation, Inc., produced a prototype designated NA-40-1. The moving force behind the design was the company’s brilliant president and chief designer, James H. “Dutch” Kindelberger, a West Virginia-born World War I aviator. He was also responsible for the legendary P-51 Mustang fighter, arguably the best fighter plane of the conflict.

Powered by two 1,100-horsepower Pratt & Whitney engines, the forerunner of the B-25 Mitchell bomber, had a shoulder-wing design, a tricycle landing gear, and was capable of carrying a 1,200-pound bomb load. Its armament consisted of .30-caliber machine guns in the nose, dorsal, and ventral positions. Built at the company’s Inglewood, California, plant, the prototype was first flown by test pilot Paul Balfour in January 1939. The engines were soon replaced by 1,300-horsepower Wright Cyclones, the plane was redesignated NA-42, and it was delivered to Wright Field in Ohio in March 1939 for USAAC evaluation.

Although the prototype crashed two weeks later because of pilot error, the Air Corps was impressed with the NA-42 design, although some changes were requested, including an increase in the bomb load and armament. North American was engaged to continue development under the basic design, NA-62, and this was completed in September 1939, when war broke out in Europe.  An immediate contract called for 184 bombers, now designated B-25.

Several improvements were made.  The wing was relocated to a mid-position, operating weights and the bomb load were increased, a tail gun position was added, and the engines were upgraded to 1,700-horsepower Wright Cyclone radials. Self-sealing fuel tanks and crew protection armor plating were added later.  Stability problems were solved by giving the plane a gull wing.

Building a B-25

Building a B-25 Mitchell was a complex and lengthy matter. Half the size of a Consolidated B-24 Liberator heavy bomber, it contained 165,000 separate items, not counting the 150,000 rivets that held it together. By 1944, the average cost of the Mitchell was $142,194, or $50,000 less than its successor, the Martin B-26 Marauder.

The B-25, which continued to undergo many further improvements, had a crew of four to six men, weighed 35,000 pounds, was 53 feet long, had a wingspan of 68 feet, and carried a 3,000-pound bomb load. Its top speed was 272 miles per hour at 13,000 feet, its service ceiling 24,200 feet, and its range 1,350 miles.

The U.S. Army Air Forces accepted a total of 9,816 B-25s produced at North American’s Inglewood and Kansas City, Kansas, plants, but it never had more than 2,700 on hand at any one time during World War II because of the numbers supplied to other American and Allied air units.

The first production model of the B-25 Mitchell bomber was test flown on August 19, 1940, and 40 further improved B-25As were built. This was the first Mitchell variant to see operational service, with the 17th Medium Bombardment Group based at McChord Field, Washington. The planes flew antisubmarine patrols, and their first kill was notched on Christmas Eve, 1941, when a Japanese submarine was sunk off Puget Sound on the U.S. West Coast.

B-25s in Action

More Mitchells went into action in 1942 and soon proved their worth with American and Allied air units. B-25V variants were among U.S. reinforcements sent to Australia, where they served with the 13th and 19th Squadrons of the 3rd Bombardment Group, and others were pressed into service with the U.S. Navy, the U.S. Marine Corps, the Dutch, Brazil, the Soviet Air Force, China, and the British Royal Air Force.

The advent of the B-25 enabled the hard-pressed RAF to replace the Bristol Blenheims, Douglas A-20 Bostons, and Lockheed Venturas flown by its No. 2 Group on daylight operations over northwestern Europe. Although Mitchells were not assigned to the U.S. Eighth Air Force in England, 712 of them were earmarked for seven RAF squadrons. The RAF crews loved the sturdy, reliable B-25 as much as their American counterparts.

As the Allies went on the offensive in 1942 and 1943, increasing numbers of Mitchells fought in almost every combat theater, manned by American, British, Australian, Canadian, Dutch, Chinese, Polish, and Soviet crews. They bombed and strafed ground targets, blasted enemy shipping, supported amphibious invasions, and were also used as trainers, transports, and photoreconnaissance planes.

 Wherever it was deployed, the maneuverable B-25 was one of the deadliest and most effective weapons in the Allied aerial arsenal. Carrying 3,000 pounds of bombs or eight five-inch rockets and bristling with a dozen .50-caliber machine guns, it proved to be virtually indispensable. Because of its firepower, it did not require fighter escort.

As the war progressed, the B-25 underwent many modifications, chiefly in its armament.  Cannons and glide torpedoes were mounted, and some were even equipped with 75mm field guns. The gun proved effective in dealing with ground targets and enemy submarines, but was eventually replaced by machine guns. In the end, Mitchells carried almost every combination of guns and bombs that their pilots and crews could imagine.

In the China-Burma-India Theater, the USAAF’s 341st Bomb Group found that the B-25s were so rugged that they could operate from makeshift dirt and grass airstrips, range far behind Japanese lines, and strike supply dumps at low level. In the Pacific Theater, Mitchells of the 345th Bomb Group operated at relatively long range, attacked Japanese ships at wave-cap altitude, and survived direct hits from small arms fire.

Workhorse Medium Bombers: Devastating Daylight Attacks Against German and Italian Installations

Clad in yellowish desert camouflage, meanwhile, B-25s were widely used in the Mediterranean Theater. In July 1942, Mitchells of the U.S. 12th Bombardment Group joined Maj. Gen. Lewis H. Brereton’s Middle East Air Force (later Ninth Air Force) at Fayid in northern Egypt. B-25s supported British Eighth Army forces at Alam Halfa and in the great Battle of El Alamein on October 23, 1942, the first major Allied victory of the war, and helped to clear the skies for Operation Torch, the three-pronged invasion of North Africa, the following November.

The workhorse medium bombers then bombed and strafed in some of their heaviest fighting of the war. While RAF Vickers Wellington bombers kept up the pressure at night and A-20s mounted their famous “Boston Tea Parties,” the British and American Mitchells carried out devastating daylight attacks on German and Italian troop concentrations, convoys, panzer columns, airfields, bridges, marshaling yards, and the port areas of Sfax, Sousse, Tunis, La Goulette, and Bizerte.  The Allied air groups in North Africa gained almost absolute supremacy over the Luftwaffe.

Once the Allies had vanquished the German Afrika Korps and its Italian allies in May 1943 and the Mediterranean war shifted to Sicily and Italy, Mitchells joined the action from bases in Sardinia and Corsica. A bombardier in one of the USAAF B-25 groups, Joseph Heller, related his experiences in a satirical novel, Catch-22.  The best-seller was published in 1955.