Em geral William “Billy” Mitchell was the most outspoken advocate of American air power in the 1920s. He argued that aircraft could sink battleships and that air power would decide future wars — and proved the first point in 1921 by having bombers sink the captured German battleship Ostfriesland. His relentless public criticism of army and navy leadership led to a famous court-martial in 1925, and he left the service. Vindicated after his death by the very air war he predicted, Mitchell was honoured when North American named its new medium bomber the Mitchell — the only US military aircraft named after a specific individual.

Frustrated that medium bombers dropping from altitude rarely hit ships, Fifth Air Force engineer Major Paul “Pappy” Gunn field-modified B-25s in Australia and New Guinea: he stripped the bombardier station and bolted a battery of forward-firing .50-calibre machine guns into a solid nose, added guns in blisters on the fuselage sides, and cleared the aircraft to attack at masthead height. Crews combined this firepower with skip-bombing — bouncing bombs across the water into a ship’s hull — a tactic developed with RAF and Australian help. North American adopted the changes into factory-built strafer versions of the B-25G, H and J.

Although the Mitchell is most associated with the Pacific, it fought everywhere. The RAF received nearly 900 Mitchells and flew them with No. 2 Group against targets in occupied Europe from 1943; Dutch crews of No. 320 Squadron flew alongside them. The Soviet Union was a major Lend-Lease recipient, using the B-25 as a long-range and night bomber on the Eastern Front. Mitchells also served US and Allied units across the Mediterranean and North Africa, and with China, Australia, Canada and Brazil — a genuinely global bomber.

In wartime the Mitchell was prized as much for its price as its performance. Period figures commonly place a late-war B-25 at roughly $96,000–$116,000 — a fraction of a four-engine heavy like the B-29 — though exact numbers vary by source and year and should be read as estimates. No official cost-per-flight-hour figure exists for wartime operations. Today, keeping one of the ~30 airworthy Mitchells flying is a serious undertaking: warbird operators commonly cite something on the order of a few thousand dollars per flight hour in fuel, oil and maintenance for a twin-radial bomber — again, an operator estimate rather than a published figure.