25 People Who Changed the Course of World War II

More than 100 million men and women mobilized. Some 70 million killed. World War II was history’s deadliest war, fought on a scale previously unimaginable. So it can be hard to conceive that victory or defeat still depended on the actions of individuals, such as the 25 listed here, who made the strategic decisions, led the battles, managed the logistics and gathered the intelligence.

“By recording lives caught up in the extraordinary circumstances of World War II,” says historian Iain MacGregor, author of The Hiroshima Men, “we recover not sentimentality but truth: that history is not made by the masses alone, but by singular people enduring, suffering and surviving within it .”

Adolf Hitler’s actions helped ensure that World War II was history’s deadliest war. As Germany’s ruler, he initiated the Holocaust—the state-sponsored genocide of more than 6 million Jews and millions of others—and triggered war in Europe with the 1939 invasion of Poland. Hitler gambled that Britain and France would not intervene, but he was wrong. His failure to defeat Britain led to another strategic miscalculation: invasion of the Soviet Union. His declaration of war on the United States ultimately hastened Germany’s defeat. Hitler died by suicide in April 1945 as Berlin fell.

The Soviet Union’s totalitarian leader, Joseph Stalin, weakened his military before the war by purging Red Army officers, and in 1941, ignored warnings of a German invasion. Yet his brutal regime proved capable of extraordinary mobilization: relocating vital arms factories to safety in the East, driving a massive increase in production and sustaining resistance. Stalin’s pragmatism—rehabilitating the purged officers, cooperating on Lend-Lease agreements with his former capitalist foes—and Soviet victories at Stalingrad and Kursk proved decisive in Nazi Germany’s defeat.

“President Roosevelt’s contribution to the Allied victory was completely irreplaceable,” says Phil Craig, World War II historian and author of 1945: The Reckoning. “He was a great war leader, a picker of men and delegator.” He transformed the United States into the “arsenal of democracy” and oversaw the massive build-up of its military. His Lend-Lease agreements helped keep Britain and other allies fighting before U.S. entry into the war, while the Atlantic Charter helped define Allied war aims and gave the Allies a moral purpose. He forged and maintained the Grand Alliance with Churchill and Stalin to coordinate the fight against Nazi Germany and Imperial Japan.

British Prime Minister Winston Churchill defied Hitler’s calls to surrender after France fell in June 1940 and led the U.K. through the Battle of Britain, a turning point that thwarted German invasion plans. Though British forces suffered humiliating setbacks elsewhere, Churchill secured vital support from Roosevelt through the Lend-Lease Act and the Atlantic Charter, helping to ensure British victory at the Battle of El Alamein and D-Day. At the same time, he helped create the Grand Alliance with Roosevelt and Stalin that ultimately defeated Nazi Germany in April 1945.

Roosevelt was a hard act to follow, but his vice president Harry S. Truman rose to the occasion, playing a key role in ending the war after Roosevelt’s April 1945 death. Truman oversaw Germany’s unconditional surrender in May and issued the Potsdam Declaration, demanding Japan’s capitulation. His decision to use atomic weapons on Hiroshima and Nagasaki hastened the end of the war in the Pacific, though their necessity remains debated by historians.

Appointed prime minister of Japan in October 1940, Hideki Tojo tightened military control over Japanese society and supported both the attack on Pearl Harbor and the expansion of the war into Southeast Asia. But he underestimated U.S. industrial power and the risks of a prolonged conflict. “Tojo encapsulated the ruthlessness, bravery and ambition of the Japanese in those early years,” says Craig. “Later, ruthlessness gave way to cruelty toward his own men as well as the enemy.” After Japan’s defeat, he was tried and executed for war crimes in 1948.

As leader of Nationalist (Kuomintang) China, Chiang Kai-shek directed resistance to Japan during a brutal invasion that killed over 20 million Chinese people. Despite internal political strife and logistical challenges—U.S. supplies could only reach his forces along the long and treacherous Burma Road or by airlift over the Himalayas—his forces pinned down more than half the Japanese army in China, limiting their ability to deploy elsewhere. This helped earn China status as a major Allied power.

A decisive player in the German war effort, Field Marshal Rommel rose to prominence following the German victory at the Battle of Arras in France 1940. While commanding the Afrika Korps in 1941-42, he achieved victories in North Africa that earned him the moniker “the Desert Fox”—and respect of the British, who eventually defeated him, led by the formidable British General Bernard Montgomery. Rommel also coordinated defenses on the French coast in advance of the Allied D-Day landing—an effort hampered by logistical shortages and command disputes. “Rommel’s drive and energy ensured a series of remarkable victories against the British in the early stages of the war,” says military historian Anthony Tucker-Jones, author of Rhineland: Hitler’s Last Defence 1944-45. “His lack of resources and ill health, though, proved his ultimate enemy as a commander.”

German general Heinz Guderian earned fame as “a leading architect of blitzkrieg,” says Philip Blood, military historian and author of War Comes to Aachen: The Nazis, Churchill and the ‘Stalingrad of the West.’ His combined use of fast-moving tanks, motorized infantry and aerial support quickly broke through enemy lines and encircled their positions, enabling early Nazi victories in Poland, France and the Soviet Union. “But Guderian’s vision … was ultimately constrained by the limited capabilities of Germany’s war industry and repeated clashes with Hitler,” says Blood.

As commander in chief and chief of naval operations, Admiral Ernest King made possible the U.S. Navy’s victory at sea. He ably balanced two competing priorities: the Navy’s need to go on the offensive against Japan with the demands of Roosevelt’s “Germany First” strategy. To stop Karl Dönitz’s U-boat wolfpacks from disrupting the D-Day buildup, King reorganized the U.S. Navy’s anti-submarine warfare effort and used secret ULTRA intelligence to track down German U-boats.

Mastermind of the Japanese attack on Pearl Harbor, carrier warfare pioneer Admiral Yamamoto believed that war between Japan and the United States was inevitable. So, he planned the first-strike surprise attack on America’s Pacific stronghold, which dramatically sank several U.S. battleships and transformed a regional Asian conflict into a global war. “But Yamamoto knew the attack had missed its most important targets: the American carriers,” says Ronald Drabkin, author of upcoming biography Admiral Yamamoto. Six months later, these carriers decisively defeated Yamamoto’s at the Battle of Midway. In 1943, the admiral was killed when his plane was ambushed by U.S. fighters.

After impressively defeating the Japanese in Mongolia in 1939, General Zhukov was tapped by Stalin in October 1941 to do the seemingly impossible: halt the German advance on Moscow. In January 1942, Zhukov launched a massive counteroffensive against the Germans, defeated them and shattered the myth of German invincibility. “He was instrumental in saving Moscow and Leningrad from Hitler’s grasp, masterminded Operation Bagration and led the Red Army to victory in the storming of Berlin in 1945,” says Tucker-Jones.

General Marshall played a central role in the Allies’ ultimate victory. He expanded the U.S. Army from around 200,000 in 1939 to 8 million by 1945, oversaw Allied strategic planning and coordination and selected the winning U.S. Army commanders, including Eisenhower, Omar Bradley and George C. Patton. Crucially, Marshall also built up the global logistics chain the U.S. Army needed to fight in Europe and Asia.

As Supreme Allied Commander in Europe, Eisenhower constantly employ his skills as coalition builder able to smooth over egos, challenge prejudices and balance priorities. He led the liberation of North Africa, which opened a path for the Allies into the Mediterranean, oversaw the D-Day invasion and the final push into Germany—and made the controversial decision not to race the Russians to Berlin. “Eisenhower may not have been as brilliant a tactical general as Patton and Montgomery,” says Craig, “but he was a first-class manager of men like them and of the material they needed.” His leadership secured Allied victory.

As commander in chief of the U.S. Pacific Fleet, Nimitz played a crucial role in the defeat of Imperial Japan. In addition to strategizing the American victory at the Battle of Midway, he also spearheaded the U.S. Navy’s successful island-hopping strategy of bypassing Japanese military strongholds to capture strategic but less well-defended islands, culminating in the American victories at Iwo Jima and Okinawa. Nimitz successfully managed strategic disagreements with the brilliant but narcissistic General Douglas MacArthur to secure a two-front advance against the Japanese homeland.

General Arnold transformed the U.S. Army Air Forces into the largest aerial fighting group in the world. By 1945, he had grown a force of 20,000 personnel and 1,000 combat aircraft to 2.4 million personnel and around 80,000 aircraft. Arnold drove through the development of the B-29 Superfortress to bomb Japan. “He believed that air power alone would deliver the United States victory,” says MacGregor. “His vision, resistance and ruthless ambition meant he had built the world’s most powerful and destructive air force by the war’s end.”

Architect Speer planned Germania, Hitler’s vision for Berlin and later served as the Reich’s armaments minister, dramatically increasing German war production despite relentless Allied bombing. “Hitler celebrated Speer as a genius,” says Blood, “but he is better understood as an efficient wartime manager whose success relied on coercion and exploitation [of 7 million forced laborers] rather than technical brilliance.” Yet in April 1945, Speer defied the Führer’s “Nero Decree” to destroy all German infrastructure.

In May 1940, Churchill appointed Canadian Max Aitken, 1st Baron Beaverbrook, as the first minister of aircraft production. A gifted and respected manager who had built his own media empire, Beaverbrook “had a flair for talking to the unions and was able to rapidly increase aircraft production,” says Craig, with British factories soon outproducing their German counterparts. His work helped ensure that the Royal Air Force (RAF) maintained its air superiority over British territory and prevented a German invasion.

In May 1940, Roosevelt asked William S. Knudsen, president of General Motors, to convert U.S. industry to war production. So, he applied mass-production techniques from the auto industry to the production of tanks, bombers and ships. Industrialist Henry J. Kaiser applied these techniques to the building of “Liberty” cargo ships, reducing the building time for a ship from 230 days to less than three weeks. Together, their work gave Allies overwhelming resource superiority.

While less of a household name, Alan Brooke played a key role in World War II as Britain’s chief military strategist. He served as a steady hand to Allied leaders, restraining Churchill’s riskier schemes, such as an invasion of Norway, and the United States’ more aggressive plans, such as invading France in 1943. He pushed the Allies to pursue a realistic strategy in the Mediterranean, focused on weakening the Axis forces and helped position General Montgomery for victory at the crucial Battle of El Alamein.

Overseeing the vast Manhattan Project, the high-pressure American sprint to build and deploy an atomic weapon, Lieutenant General Leslie Groves managed the secrecy, resources and vast industrial effort, which entailed more than 100,000 people in some 30 locations across the country. He delivered the atomic bombs on time and changed how the war would end. “Driven, relentless and fiercely protective of his mission, he carried the crushing burden of the expectation that the Manhattan Project would deliver victory,” says MacGregor, “which he had to balance against his knowledge of its terrible cost.”

Posing as a German journalist in Japan, Soviet spy Richard Sorge warned of Germany’s 1941 invasion—which Stalin ignored—and confirmed that Japan would not attack the Soviet Union. This allowed Stalin to transfer troops West from Siberia to defend Moscow—a turning point in the war. Eventually captured, Sorge was tortured and executed by the Japanese; Stalin refused to intervene. He was posthumously awarded the title of Hero of the Soviet Union.

Mild-mannered Juan Pujol García (Agent Garbo) was possibly “the greatest double agent of World War II.” Working for Britain, the Spaniard ran a network of 27 fictitious agents to deceive German intelligence. His misinformation convinced the Nazis that the Normandy landings were a diversion for a much greater Allied invasion further along the coast; as a result, Hitler kept 350,000 troops stationed there for two more months.

American spy Virginia Hall, deemed the “most feared” Allied agent by the Gestapo, stands as one of World War II’s most successful operatives. She helped organize French resistance groups into an effective fighting force, ambushed Nazi convoys, orchestrated prison breaks and escaped over the Pyrenees with the Germans in hot pursuit. “Virginia Hall disdained glory and publicity,” says Sonia Purnell, author of A Woman of No Importance. “Her derring-do was viewed in London with ‘stupefaction,’ and she did all this while dependent on a primitive wooden leg.”