The 16 Biggest Military Invasions of the Last Century

Nazi Germany’s unexpected assault on Poland on Sept. 1 1939 marked the beginning of WWII. German battalions launched the unanticipated offensive on Poland as northern forces sprung from Pomerania and East Prussia, while the southern contingents penetrated the south of Poland from Silesia and Slovakia. The Red Army of the Soviet Union moved in from the east on Sept. 17, and Poland was then partitioned between the Nazis and the Soviets according to the Nonaggression Pact signed by the two forces ahead of the invasion.

In May 1940, Germany launched an invasion of the Low Countries — Belgium, the Netherlands, and Luxembourg — and France, bypassing central Belgium and instead using the Ardennes Forest route. Overcoming French defenses swiftly, the Germans reached the coast, leading to Belgian and Dutch capitulation. A large-scale evacuation of British and French troops from Dunkirk ensued. Paris fell in June, and a subsequent armistice resulted in German occupation of northern France and the Atlantic coastline, with a new French government established in Vichy.

Operation Barbarossa, launched on June 22, 1941, was Nazi Germany’s ambitious strategy to invade the Soviet Union, violating the Nonaggression Pact of 1939. Unleashing roughly 3 million troops, it is historically the largest military offensive. However, the rigorous Russian winter and staunch Soviet resistance foiled Nazi ambitions, making Operation Barbarossa a catastrophic failure that drastically reversed Germany’s fortunes in the war.

In August 1942, the U.S. performed its first major amphibious assault of WWII at Guadalcanal, capturing a strategic airfield. This led to intense battles as both sides sought control of Henderson Field. By March 1943, American forces, after a fierce struggle, successfully took over the island, marking a significant step in repelling the Japanese in the Pacific. This victory laid the groundwork for the island hopping strategy, bypassing heavily fortified islands for more vulnerable locations, accelerating the Allied invasion across the Pacific.

D-Day, on June 6, 1944, kicked off this operation to invade and liberate the European mainland from the Nazi Germany. Allied Forces deployed in Northwestern France and secured a foothold in Normandy. This invading force comprised roughly 200,000 soldiers and is considered the largest amphibious invasion in history. This operation marks the key turning point in the Western Theater, when the Allied Forces were able to push back the Axis Powers and eventually prevail in the war, even at great cost.

Following Japan’s withdrawal from Vietnam, Nationalist leader Hồ Chí­ Minh proclaimed its independence. France refused to recognize it, launching a military invasion to regain control of the country and to reestablish its colonial authority, setting off the French Indochina War. The first few years of this war were characterized by low-level rural insurgency against the French occupation. Tensions escalated in 1946, when French naval forces bombarded Haiphong, killing thousands of civilians. This later culminated in the Geneva Accords of 1954, dividing Vietnam into North and South — marking the end of French colonial influence, but sowing the seeds for the Vietnam War.

In 1950, Chinese troops seized control of eastern Tibet, quashing the under-resourced Tibetan forces. The international community did not intervene despite the Dalai Lama’s appeals. A coerced treaty in 1951 enabled Chinese civil and military establishments in Lhasa, promising Tibetan autonomy and religious freedom. However, by 1959, resistance to Chinese oppression had escalated into a major uprising in Lhasa, which was ultimately unsuccessful, leading to the Dalai Lama’s escape through the Himalayas to India. This mountain nation is still under Chinese rule to this date.

The Bay of Pigs invasion of Cuba in 1961 was a failed attempt by CIA-trained Cuban exiles to overthrow Fidel Castro’s government. U.S. President John F. Kennedy withdrew vital air support at the eleventh hour to maintain America’s deniability, leaving the ill-prepared rebels exposed. The invasion was swiftly crushed by Castro’s forces within 72 hours, bolstering Castro’s position and severely damaging U.S.-Cuba relations.

The 1965 India-Pakistan War marked the second major conflict over the contested region of Jammu and Kashmir. The escalation began when Pakistani forces attempted an unsuccessful seizure of the territory, resulting in intensified hostilities. The conflict, however, reached a stalemate, leaving the issue of Kashmir’s status unresolved, with lasting implications for the region’s dynamics.

In the Six-Day War in June 1967, Israel achieved a swift victory against Arab forces. In a surprise pre-emptive strike, Israel decimated over 90% of Egypt’s air force, leaving Egyptians ground troops exposed. Within days, Israel seized key territories, including the Sinai Peninsula, Gaza Strip, West Bank, Jerusalem’s Old City, and the Golan Heights. This fast-paced conflict significantly reshaped the dynamics of the Arab-Israeli dispute.

The Tet Offensive was a coordinated series of attacks by approximately 85,000 North Vietnamese troops. Launched against five key South Vietnamese cities, various military bases, and numerous towns and villages, it marked a significant military operation during the Vietnamese New Year. Despite being a tactical failure for the North, it had profound psychological effects, particularly within the American political sphere and public sentiment. The American public’s negative reaction to the Tet Offensive ultimately led to the Nixon Administration pulling forces from South Vietnam in 1973.

In December 1979, the Soviet Union invaded Afghanistan to support its communist government against anti-communist Muslim guerrillas, known as the mujahideen. The invasion involved 30,000 Soviet troops, who ousted then-President Hafizullah Amin. Despite the Soviet Union’s intent to stabilize its client state, resistance intensified, with the mujahideen rebellion spreading across the country. The conflict persisted until the Soviet withdrawal in February 1989.

In 1982, Argentina’s military junta, led by Lt. General Leopoldo Galtieri, abruptly ended negotiations with Britain and launched an invasion of the Falkland Islands. The regime believed reclaiming the islands would foster national unity amidst critiques of economic blunders and human rights violations. A well-trained invasion force was mobilized. In response, Britain declared a war zone around the Falklands and assembled a naval task force.

In October 2001, in response to the 9/11 terrorist attacks, the U.S., along with British support, launched Operation Enduring Freedom, targeting Taliban forces in Afghanistan. The campaign, primarily involving air strikes, was bolstered by U.S. special forces, the Northern Alliance, which included , and anti-Taliban factions. Ground forces arrived 12 days later, mostly engaging in combat against the Taliban. A significant episode was the Battle of Tora Bora in December, when Afghan militias fought al-Qaeda militants, resulting in bin Laden’s eventual escape.

In March 2003, coalition forces led by the U.S. launched an air and ground invasion of Iraq. The aim was to dismantle supposed weapons of mass destruction and end Saddam Hussein’s regime. The Iraqi Army was swiftly overwhelmed, but resistance continued. Baghdad fell to the coalition within three weeks. Major combat concluded in just over a month, with President George W. Bush announcing the end of major operations in May 2003.

On Feb. 24, 2022, Russia began a widespread invasion of Ukraine, launching missile strikes on various cities. Swiftly advancing, Russian forces captured vast Ukrainian territories, even reaching the outskirts of Kyiv. Despite taking control of regions in the east and south, including Kherson, and encircling Mariupol, the Russians encountered intense Ukrainian resistance and logistical issues, resulting in shortages of supplies and demoralized troops.