The Dieppe Raid of August 1942 was a bold but disastrous Allied assault on the German-held French port of Dieppe. Intended to test coastal defences and gather intelligence for future invasions, it ended in catastrophe: nearly 60% of the 6,000 troops—mostly Canadian—were killed, wounded, or captured. Tanks bogged down on the shingle beach, naval support faltered, and air cover proved inadequate. Yet the operation’s failure provided vital lessons in planning, fire support, and intelligence that directly shaped the success of the successful amphibious assaults to come. Dieppe was a tragedy—but one that taught the Allies how to win.