Military history of the United States during World War II

While officially neutral, the U.S supplied Britain, the Soviet Union, and China with war materiel through the Lend-Lease Act signed into law on 11 March 1941, and deployed the U.S. military to replace the British forces stationed in Iceland.

Although President Franklin D. Roosevelt personally favored a more assertive foreign policy, his administration remained committed to isolationism during the 1930s to ensure congressional support for the New Deal, and allowed Congress to pass the Neutrality Acts.

[7] In August 1941, President Roosevelt and Prime Minister Churchill met aboard the USS Augusta at Naval Station Argentia in Placentia Bay, Newfoundland, and produced the Atlantic Charter outlining mutual aims for a postwar liberalized international system.

[14] Another notable example was the Flying Tigers, created by Claire L. Chennault, a retired US Army Air Corps officer working in the Republic of China since August 1937, first as military aviation advisor to Generalissimo Chiang Kai-shek in the early months of the Sino-Japanese War.

[15] In 1942 President Franklin D. Roosevelt set up a new command structure to provide leadership in the US Armed Forces while retaining authority as Commander-in-Chief as assisted by Secretary of War Henry Stimson with Admiral Ernest J.

The senior Allied leadership was primarily to blame for the loss as internal bickering between American General Lloyd Fredendall and the British led to mistrust and little communication, causing inadequate troop placements.

From August 1944 to March 1945 the Allies managed to breach the formidable defenses but they narrowly failed to break out into the Lombardy Plains before the winter weather closed in and made further progress impossible.

The USAAF Eighth Air Force's B-17 bombers were called the "Flying Fortresses" because of their heavy defensive armament of ten to twelve machine guns, and armor plating in vital locations.

Nevertheless, the sheer tonnage of explosives delivered by day and by night was eventually enough to cause widespread damage, and, more importantly from a military point of view, forced Germany to divert resources to counter it.

Doolittle's major influence on the European air war occurred early in the year when he changed the policy requiring escorting fighters to remain with the bombers at all times.

This strategy fatally disabled the twin-engined Zerstörergeschwader heavy fighter wings and their replacement, single-engined Sturmgruppen of heavily armed Fw 190As, clearing each force of bomber destroyers in their turn from Germany's skies throughout most of 1944.

The beach is on the coast of Normandy, France, facing the English Channel, and is 5 miles (8 km) long, from east of Sainte-Honorine-des-Pertes to west of Vierville-sur-Mer on the right bank of the Douve River estuary.

The US VII Corps immediately began making their push after the beaches were secured on 6 June, facing a mix of weak regiments and battlegroups from several divisions who used the bocage terrain, flooded fields and narrow roads to their advantage which slowed the American advance.

The defending German force attempted to hold the city long enough to allow reinforcements en route from the south to arrive, prevent or delay the merging of the lodgments, and keep the US First Army from launching an attack towards Lessay-Périers that would cut off the Cotentin Peninsula.

Initially successful, its attack was thrown back by Combat Command A (CCA) of the US 2nd Armored Division After the amphibious assault, the Allied forces remained stalled in Normandy for some time, advancing much more slowly than expected with close-fought infantry battles in the dense hedgerows.

On 16 December 1944, the Germans launched a massive attack westward in the Ardennes forest, along a battlefront extending southwards from Monschau to Echternach, hoping to punch a hole in the Allied lines and capture the Belgian city of Antwerp.

Commander Minoru Genda, the chief planner of the raid, begged Nagumo to strike again at the shore facilities, oil storage tanks, and submarines, and to hunt down the American carriers that were supposedly nearby.

Tokyo's calculation that the Americans would lose heart and seek a compromise peace proved wildly wrong—the "sneak attack" electrified public opinion, committing America with near unanimity to a war to the death against the Japanese Empire.

An excerpt from the Naval War College Review says that "although the Coral Sea fight was a marginal tactical victory for the IJN [Imperial Japanese Navy], in terms of ships and tonnage sunk, it amounted to a small strategic triumph for the U.S.

Runways, hangars, radar stations, power generators, barracks, gasoline storage tanks and ordnance dumps had to be built hurriedly on tiny coral islands, mud flats, featureless deserts, dense jungles, or exposed locations still under enemy artillery fire.

The men who had been at jungle airfields longest, the flight surgeons reported, were in a bad shape: The Marines had their own land-based aviation, built around the excellent Chance-Vought F4U Corsair, an unusually large fighter-bomber.

Mobility was a basic mission of Marine ground forces; they were too lightly armed to employ the sort of heavy artillery barrages and massed tank movements the Army used to clear the battlefield.

On 11–12 October 1942, to disrupt Japanese attempts to reinforce and resupply their troops on Guadalcanal (nicknamed the "Tokyo Express"), a small US naval force attacked this supply line at the Battle of Cape Esperance and succeeded.

Marines and soldiers landed unopposed on 1 April 1945, to begin an 82-day campaign which became the largest land-sea-air battle in history and was noted for the ferocity of the fighting and the high civilian casualties with over 150,000 Okinawans losing their lives.

The Boeing B-29 Superfortress boasted four 2,200 horsepower Wright R-3350 supercharged engines that could lift four tons of bombs 33,000 feet (high above Japanese flak or fighters), and make 3,500-mile round trips.

Expecting increased resistance, including far more Kamikaze attacks once the main islands of Japan were invaded, the US high command rethought its strategy and used atomic bombs to end the war, hoping it would make a costly invasion unnecessary.

On the afternoon of 7 December 1941, six hours after the Japanese attack, US naval commanders in the Pacific were ordered by the US Navy Chief of Staff to "execute unrestricted air and submarine warfare against Japan".

A fear in the American high command was that an invasion of mainland Japan would lead to enormous losses on the part of the Allies, as casualty estimates for the planned Operation Downfall demonstrate.

As Japan was able to withstand the devastating incendiary raids and naval blockade despite hundreds of thousands of civilian deaths, President Harry Truman gave the order to drop the only two available atomic bombs, hoping that such sheer force of destruction on a city would break Japanese resolve and end the war.

In slightly more than five months of combat in 1944, the Marauders advanced 750 miles through some of the harshest jungle terrain in the world, fought in five major engagements, mostly behind enemy lines, with or in support of British Empire and Chinese forces in Burma and suffered many casualties.