The Avro Lancaster emerged in 1941 as Britain’s answer to the shortcomings of the earlier Avro Manchester. Designed by Roy Chadwick, it used four Rolls-Royce Merlin engines and quickly became the backbone of RAF Bomber Command. First entering service in 1942, it soon replaced the Stirling and Halifax as the RAF’s main heavy bomber, capable of long-range missions over Germany. With its capacious 33-foot bomb bay, the Lancaster could carry weapons that no other Allied aircraft could, including 4,000 lb, 8,000 lb, and 12,000 lb “blockbuster” bombs. Its versatility also allowed it to deliver Barnes Wallis’s special weapons—the “bouncing bomb” for Operation Chastise in 1943, and later the 12,000 lb Tallboy and 22,000 lb Grand Slam “earthquake” bombs, making it the heaviest bomber of the war in payload capacity. Structurally, the Lancaster was a mid-wing monoplane of five fuselage sections and strong all-metal construction, designed for both durability and ease of mass production. Crewed by seven men, the Lancaster combined robustness with smooth handling, often praised by pilots as a “delightfully easy aeroplane to fly.” Yet it had weaknesses: its escape hatches were small, making bailing out difficult, and early variants suffered structural failures when pushed beyond design limits. In combat, the bomber relied on four hydraulically operated turrets, most armed with twin or quadruple .303 Browning machine guns. Rear gunners bore the brunt of Luftwaffe night fighter attacks, and although experimental heavier turrets with .50-caliber guns were tried, losses remained high until radar-assisted “Village Inn” gun-laying turrets were introduced late in the war. The Lancaster flew more sorties and dropped more bombs than any other RAF heavy bomber, delivering over 600,000 tons across Europe. Its most famous mission was the Dambusters raid of May 1943, when specially modified Lancasters of 617 Squadron breached Ruhr Valley dams with bouncing bombs. After the war, it was adapted for new roles: maritime patrol with the Avro Shackleton, aerial refueling, photo-reconnaissance, and civilian service as the Avro Lancastrian airliner. Though replaced in frontline service by the Avro Lincoln, the Lancaster’s wartime record secured its place as one of the most effective and iconic bombers of the Second World War.