• Longest military campaign of World War II
• U.S. involvement began before the formal U.S. declaration of war on Germany
• Attempted blockade of the United Kingdom and the Soviet Union through attacks on merchant shipping and Allied naval ships bringing supplies and military reinforcement from North America
• Allied victory achieved through implementation of convoy system
• Eventually resulted in Allied naval superiority over German surface raiders and U-boats.

Germany

Italy

• first involvement of American forces in Mediterranean and Middle East theatre
• first major American airborne assault
• resulted in Free French control of French West Africa and Anglo-American occupation of western French North Africa
• lead to full German occupation of Vichy France

• resulted in major reorganization of the U.S. Army
• resulted in delay of planned amphibious invasion of France

• first battle of Allied invasion of Sicily
• resulted in increased prioritization of naval artillery support

• first battle of the Allied invasion of mainland Italy

• resulted in controversial bombing of Monte Cassino Abbey
• resulted in defeat of the Senger Line

• resulted in heavy fighting
• allowed the German Tenth Army to withdraw to the Gothic Line

• successfully established Allied beachhead in France and neutralized the Atlantic Wall
• resulted in withdrawal of German forces in northern France to Paris

• Failed in objective to capture Graignes
• Followed by Waffen-SS massacre of American prisoners of war

• Consolidated American beachheads against German counterattack
• allowed seizure of the Cotentin Peninsula

• Resulted in seizure of Brest
• German sabotage prevented use of port facilities

• Allied capture of Southern France
• Free French recapture of Toulon and Marseille
• withdrawal of Army Group G from Southern France through the Rhône River Valley to the Vosges

• American capture of Nancy and crossing of the Moselle River

• Successfully liberated large parts of the Netherlands including Eindhoven and Nijmegen
• created a salient limiting V-2 rocket attacks
• failed in operational objective to create bridgehead across the Rhine River into Germany and end the war by the end of 1944
• Resulted in major reorientation of Western Allied military strategy

• longest ever battle fought by the U.S. Army
• Failure to capture the Rur River

• American capture of Metz
• hindered advance of U.S. Third Army

• One of largest urban battles fought by the U.S. Army during the war
• Resulted in American occupation of Aachen and destruction of much of the city
• First German city captured by the Western Allies
• Delayed Allied advance into the Ruhr Basin

• Final German offensive on the Western Front
• Caused temporary delay of Western Allied advance
• Failure in German strategic objective to recapture Antwerp, encircle Allied forces in the Low Countries, and force the Western Allies to draft a separate peace treaty
• resulted in depletion and collapse of Wehrmacht forces, ultimately accelerating Western Allied advance and capture of the Siegfried Line as well as the Soviet Union's Vistula–Oder Offensive on the Eastern Front

• Failure of German strategic objective to destroy Allied forces in Alsace and Lorraine
• Resulted in German salient in central Alsace

• Failure of German objective to recapture northern Alsace
• Resulted in full French control of Alsace

• Successful encirclement and division of Army Group B
• Surrender of German Fifteenth Army and German forces under Walter Model's command
• Western Allied occupation of the Ruhr and advance towards the Elbe River

• Allied airborne operations in Hamminkeln and Wesel to secure British invasion and occupation of northwestern Germany
• Successfully established bridgeheads on the Rhine

• Achieved Allied capture of Frankfurt

• Major General Maurice Rose is killed in battle and is the highest-ranking U.S. Armed Forces officer to be killed in action at the Western Front.

• Victory allowed U.S. Third Army advance through Hesse towards Frankfurt am Main

• House-to-house combat involving Volkssturm auxiliary units
• Resulted in American occupation of Heilbronn and the Neckar River
• Continuation of southeastern advance towards Heidelberg and Bavaria

• Most intense urban battle of the war.
• Considered a major blow to Germany.

• Planned Allied offensive towards Lombardy
• Ended with the death of Benito Mussolini and complete surrender of Axis forces
• Final battle of the Italian Campaign

• Preventive strike on the U.S. Pacific Fleet to prevent American intervention in planned Japanese offensive into Southeast Asia
• Major Japanese tactical victory resulting in the destruction of American naval ships and base installations
• Failure of Japanese objective to destroy American aircraft carriers and achieve decisive victory
• Caused the United States to formally enter World War II and declare war on Japan, Germany, and Italy
• Resulted in reorganization and buildup of the U.S. Armed Forces
• Resulted in shift in public opinion in favor of entering the war

• Successful Japanese invasion and occupation of Wake Island despite U.S. Marine Corps resistance
• Continued Japanese occupation until the end of the war

• Last stand of American and Filipino forces
• Ended in Japanese capture of Bataan Peninsula

• First American air raid against the Japanese Home Islands
• Intended as retaliation for the Pearl Harbor attack
• Minor damage to Japanese urban and military targets, including Tokyo
• Improved American morale and damaged Japanese morale

• First naval battle in history fought between aircraft carriers
• Japanese tactical victory; ended in successful invasion and occupation of Tulagi and the British Solomon Islands
• American strategic victory; prevented Japanese invasion of Port Moresby
• Resulted in damage to Japanese aircraft carriers Shōkaku and Zuikaku
• Resulted in fragility of Japanese forces in the South West Pacific

• Attempted capture of Allied airfields at Milne Bay
• Resulted in Japanese withdrawal due to unexpected participation of the First Australian Imperial Force and Allied attacks on Japanese supply lines

• Japanese attempt to fight back after the battle is over but are repelled.

• Wakde Airfield is obtained.

• Biak becomes a logistical center for the Allies.

• Resulted in withdrawal of Japanese forces after heavy fighting

• Considered by historians to be one of the most important naval battles in history
• Contributed to depletion of manpower and material of the Imperial Japanese Navy
• Failure to divert American aircraft carriers into trap and invade Midway Island in preparation for future offensives against Fiji, Samoa, and Hawaii
• Ended in destruction of four Japanese fleet carriers
• Turning point in the Pacific War resulting in Japanese retreat and American offensives

• Major Allied victory recapturing the Solomon Islands
• Ended in withdrawal of Japanese forces from the Solomon Islands
• Contributed to depletion of Imperial Japanese Army
• Forced Japanese military to end offensives and shift to defensive strategy

• Ended in retreat of Allied surface ships
• Resulted in loss of Japanese aircrews

• American amphibious landing
• Resulted in capture of Tarawa Atoll after heavy fighting

• Ended in American seizure of Kwajelein Atoll
• Provided major boost to American morale

• Ended in seizure of Eniwetok as a forward base for future offensives into the Japanese South Seas Mandate

• Ended in American occupation of Saipan
• Brought Japanese home islands within range of American B-29 Superfortress heavy bombers
• Prompted resignation of Japanese Prime Minister Hideki Tojo

• Largest carrier battle in history
• Completely eliminated Japanese ability to mount large-scale carrier operations
• Ended in Japanese withdrawal from the Philippine Sea and American offensive towards the Philippines

• Ended Japanese occupation of Guam

• Ended in American capture of Tinian as forward air base

• Ended in American capture of Peleliu as forward air base
• Controversial due to high casualty rate of the 1st Marine Division and the 81st Infantry Division alongside minor strategic value

• Ended in American capture of Angaur as forward air base

• Sometimes considered to be the "largest naval battle in history"
• Final naval battle in history fought between battleships
• Saw the introduction of Japanese kamikaze attacks
• Isolated Japanese holdings in Southeast Asia from the Home Islands
• Allied defeat of Japanese naval forces despite their full mobilization
• Commenced American offensive into the Philippines

• Highest net casualty for U.S. forces during World War II
• Resulted in Allied liberation of Luzon

• One of the most intense urban battles fought by American forces during the war
• Accompanied with massacres of Filipino civilians by Japanese forces

Philippines

• Ended in entrapment of Japanese forces under General Tomoyuki Yamashita's command

• One of the most intensive battles of the Pacific theatre
• initially controversial due to heavy casualties and low strategic value of Iwo Jima
• Ended in the American occupation of Iwo Jima aided by overwhelming military superiority, later used as an emergency landing base for American bombers
• Resulted in most of the Japanese combatants being killed in action
• Site of Joe Rosenthal's iconic photograph Raising the Flag on Iwo Jima.

• largest amphibious battle of the Pacific theatre of World War II
• Ended in heavy casualties for both sides
• Large-scale deaths of Okinawan civilians.
• Ended in U.S. occupation of Okinawa
• Intended as a preparatory battle to the abandoned Western Allied invasions of Kyūshū and Honshu.
• Heavy civilian and combat casualties may have influenced U.S. decision to use atomic bombs against Hiroshima and Nagasaki