U-boats posed the deadliest threat to Allied convoys traveling the Atlantic.

The development of the B-17 bomber, which allowed American planes to reach inside Germany and bomb its cities.

Heavily armed vessels disguised as ordinary cargo ships patrolled allied waters, sinking supply boats and stealing their content.

In 1945, Soviet and American troops press Hitler's armies from the west and the east, culminating in the fall of Berlin.

Kamikaze pilots guard the island of Okinawa from American forces.

German forces retreat across the Rhine on the Remagen bridge near the close of the war.

American forces landing on the shores of Iwo Jima encounter Japanese combatants willing to fight to the death.

The December 1944 battle pitting American forces against German Panzer divisions in the Ardennes Forest.

The Battle of the Gothic Line in 1944.

American B-29 high-altitude bomber attacks Japan near the end of World War II.

Gen. Douglas MacArthur's return to the Philippines, and the final push to retake the islands after two years of Japanese occupation.

The Allies launch an attack designed to push the Germans back to the Rhine River.

Both political and military expediency were factors in the return of the French capital to its people.

Allied Forces continue across France pushing the German troops back into Germany.

Six weeks after the D-Day invasion of the beaches of Normandy, the allied forces are pushing the Germans back through the French countryside. Town by town is won back as Panzer divisions retreat back to the Meuse River.

D-Day, the 6th of June--one of the most pivotal moments in world history. In a massive armada of thousands of ships, 3,000,000 allied troops land at Three Beaches in Normandy, France.

American forces overtake Japanese troops on the islands of Palau on the way to the Philippines.

Examining the battle at the Kwajelein Atoll in the South Pacific during 1944. Included: operations by the Seabees.

Allied armies encounter German resistance in the Italian fishing town of Anzio.

Bloody fighting erupts on a group of tiny Pacific islands in November 1943.

Allied troops are advancing through Italy and meet a stiff German defensive position in an old monastery Monte Cassino.

Bombing of Ploesti

Fresh from victory in North Africa, the Allies successfully invade the island of Sicily, staging an eventual Italian withdrawal from the war.

The Japanese meet resistance from British forces as they advance through Burma to take India in 1944.

In the North African desert in 1942, American fighting forces encounter the dreaded Rommel for the first time to stop the German war machine.

Erwin Rommel battles Allied forces in North Africa in 1942.

German forces encounter Russian resistance.

The Allies launch an ill-fated attack on the German-occupied port of Dieppe, France.

For the first time since Americans entered the war, Marines face Japanese infantrymen at Guadalcanal. In the jungles, two powerful armies clash in a six month battle that claims nearly 30,000 lives.

Only one isolated atoll prevents an enemy invasion of Hawaii. Midway Island is where the Japanese fleet converges on a tiny American base with a massive strafing and bombing attack.

American and Philippine troops and Philippine scouts take on a fast advancing Japanese invasion.

During a two-hour surprise attack on the American Pacific fleet anchored at Pearl Harbor, Japanese navy pilots score a near-complete victory.

Before the sneak attack on Pearl Harbor, the Japanese initiate the Pacific War by firing on the British in Malaya. Their route to the rubber-rich nation takes them into Singapore, the World's most armed fortress.

In 1941, Mussolini desperately wants to wrest the tiny island of Malta from the British for control of the Mediterranean. When his inadequate air force fails to bomb the Maltese into submission, Hitler's Luftwaffe joins the campaign.

After British forces withdrew in defeat from Greece to the island of Crete in early 1941, they were soon fighting German invasion armies again. This time, 5,000 of Hitler's elite paratroopers landed to complete their conquest in the Mediterranean.

German field marshal Erwin Rommel scores a major victory at the Libyan seaport of Tobruk.

Hitler has taken France and has his sights set on England. At a heavy toll, the Royal Air Force swings into action to stop Hitler from crossing the Channel.

Early in the war, the Germans decide they need to guarantee access to the Norwegian port of Narvik to ensure their supplies of Swedish iron ore. The British, however, send destroyers to up-end the German plan.

German tanks roll into Poland in September 1939.

British and Allied forces are pushed back by an overwhelming German Army. 400,000 Allied troops are trapped in the French town of Dunkirk. After several failed attempts at rescue, the British Navy was able to rescue 330,000 troops.