Italy was invaded: Newly captured North Africa was used as a springboard for the invasion of Sicily on 10 July 1943. On 25 July Mussolini was fired from office by the King of Italy, allowing a new government to take power. Having captured Sicily, the Allies invaded mainland Italy on 3 September 1943. Italy surrendered on 8 September, but German forces continued to fight. Allied forces advanced north but were stalled for the winter at the Gustav Line, until they broke through in the Battle of Monte Cassino. Rome was captured on 5 June 1944. Mid-1943 brought the fifth and final German Sutjeska offensive against the Yugoslav Partisans before the invasion and subsequent capitulation of Italy, the other major occupying force in Yugoslavia.
Asia: (1943–45) Australian and U.S. forces then undertook the prolonged campaign to retake the occupied parts of the Solomon Islands, New Guinea and the Dutch East Indies, experiencing some of the toughest resistance of the war. The rest of the Solomon Islands were retaken in 1943, New Britain and New Ireland in 1944. As the Philippines were being retaken in late 1944, the Battle of Leyte Gulf raged, arguably the largest naval battle in history. The last major offensive in the south-west Pacific Area was the Borneo campaign of mid-1945, which was aimed at further isolating the remaining Japanese forces in South East Asia and securing the release of Allied POWs. Allied submarines and aircraft also attacked Japanese merchant shipping, depriving Japan(i)s industry of the raw materials it had gone to war to obtain. The effectiveness of this stranglehold increased as U.S. Marines captured islands closer to the Japanese mainland. The Nationalist Kuomintang Army, under Chiang Kai-shek, and the Communist Chinese Army, under Mao Zedong, both opposed the Japanese occupation of China but never truly allied against the Japanese. Conflict between Nationalist and Communist forces emerged long before the war; it continued after and, to an extent, even during the war, though more implicitly. The Japanese had captured most of Burma, severing the Burma Road by which the Western Allies had been supplying the Chinese Nationalists. This forced the Allies to create a large sustained airlift, known as "flying the Hump". U.S. led and trained Chinese divisions, a British division and a few thousand U.S. ground troops cleared the Japanese forces from northern Burma so that the Ledo Road could be built to replace the Burma Road. Further south the main Japanese army in the theatre were fought to a standstill on the Burma-India frontier by the British Fourteenth Army (the "Forgotten Army"), which then counter-attacked, and having recaptured all of Burma was planning attacks towards Malaya when the war ended.
1944: The beginning of the end
On "D-Day" (6 June 1944) the western Allies invaded German-held Normandy in a pre-dawn amphibious assault spearheaded by American (82nd and 101st), British (6th) and Canadian paratroops, opening the "second front" against Germany. The allies suffered large casualties during the beach assault. German artillery batteries pounded the beaches. But the airborne divisions took out the guns from the rear, enabling the seaborne troops to break inland. 2 Hedgerows aided the defending German units, and for months the Allies measured progress in hundreds of yards and bloody rifle fights. An Allied breakout was effected at St.-Lô, and the most powerful German force in France, the Seventh Army, was almost completely destroyed in the Falaise pocket while counter-attacking. Allied forces stationed in Italy invaded the French Riviera on 15 August and linked up with forces from Normandy. The clandestine French Resistance in Paris rose against the Germans on 19 August, and a French division under General Jacques Leclerc, pressing forward from Normandy, received the surrender of the German forces there and liberated the city on August 25. By early 1944, the Red Army had reached the border of Poland and lifted the Siege of Leningrad.
Shortly after Allied landings at Normandy, on 9 June, the Soviet Union began an offensive on the Karelian Isthmus that after three months would force Nazi Germany(i)s co-belligerent Finland to an armistice. Operation Bagration, a Soviet offensive involving 2.5 million men and 6,000 tanks, was launched on 22 June, destroying the German Army Group Centre and taking 350,000 prisoners. Finland(i)s defence had been dependent on active, or in periods passive, support from the German Wehrmacht that also provided defence for the chiefly uninhabited northern half of Finland. After the Wehrmacht retreated from the southern shores of the Gulf of Finland, Finland(i)s defence was untenable. The Allies(i) armistice conditions included further territorial losses and the internment or expulsion of German troops on Finnish soil executed in the Lapland War, now as co-belligerents of the Allies, who also demanded the political leadership to be prosecuted in "war-responsibility trials", which the Finnish public perceived as a mockery of the rule of law.
Allied paratroopers attempted a fast advance into Germany with Operation Market Garden in September but were repulsed. Logistical problems were starting to plague the Allies(i) advance west as the supply lines still ran back to the beaches of Normandy. A decisive victory by the Canadian First Army in the Battle of the Scheldt secured the entrance to the port of Antwerp, freeing it to receive supplies by late November 1944. Romania surrendered in August 1944 and Bulgaria in September. The Warsaw Uprising was fought between 1 August and 2 October. Germany withdrew from the Balkans and held Hungary until February 1945.
In December 1944, the German Army made its last major offensive in the West, largely because even if successful in the east it would have had no effect on the massive Red Army rolling towards the Reich. Thus, Hitler thought he could drive a wedge between the frequently feuding Western Allies, causing them to agree to a favorable armistice, after which Germany could concentrate all her efforts on the Eastern front and have a chance to defeat the Soviets. The mission was unrealistic to begin with, since German plans largely relied on capturing Allied fuel dumps in order to keep their vehicles moving with the goal of capturing the vital port of Antwerp, and thus crippling the Allies in the Battle of the Bulge. At first, the Germans scored successes against the Americans stationed in the Ardennes. The Allied forces, largely unprepared for this sudden attack, suffered heavy casualties. In addition, the weather during the initial days of the invasion favored the Germans because the bad weather grounded Allied aircraft. However, with the overcast skies clearing allowing Allied air supremacy to enter the equation, and with the German failure to capture Bastogne, as well as the arrival of Gen. Patton(i)s Third Army, the Germans were forced to retreat back into Germany. The offensive was defeated. By now, the Soviets had reached the eastern borders of pre-war Germany.
By this time the Soviet steamroller had become so powerful that some historians argue that the U.S. and British landing at Normandy was more to prevent a coast-to-coast Soviet block than to fight Germany. In all, 80% of all German casualties were suffered on the Eastern front, and Europe became divided along Germany. Some believe that had the U.S. not invaded the sparsely defended Western Front, Stalin would have controlled all of Europe.
The bombing of Dresden by the British Royal Air Force (RAF) and the United States Army Air Force (USAAF) between February 13 and February 15, 1945 remains one of the more controversial events of World War II.
According to British historian Frederick Taylor:
"The destruction of Dresden has an epically tragic quality to it. It was a wonderfully beautiful city and a symbol of baroque humanism and all that was best in Germany. It also contained all of the worst from Germany during the Nazi period. In that sense it is an absolutely exemplary tragedy for the horrors of 20th Century warfare..."
1945: The end of the war
Europe: Churchill, Stalin, and Franklin D. Roosevelt made arrangements for post-war Europe at the Yalta Conference in February 1945. It resulted in an April meeting to form the United Nations: nation-states were created in Eastern Europe; it was agreed Poland would have free elections (in fact elections were heavily rigged by Soviets); Soviet nationals were to be repatriated, and the Soviet Union was to attack Japan within three months of Germany(i)s surrender. The Red Army (including 78,556 soldiers of the 1st Polish Army) began its final assault on Berlin on 16 April. By now, the German Army was in full retreat and Berlin had already been battered due to preliminary air bombings and such. Most of the Nazi leaders had either been killed or captured. Hitler, however, was still alive, and was slowly going mad. As a final resistance effort, he called for civilians, including children, to fight the oncoming Red Army. When this failed, Hitler went into delusion, imagining that everyone was against him and that he still had battalions of troops to send into battle. Hitler and his staff moved into the Führerbunker, a concrete bunker beneath the Chancellery, where on 30 April 1945, he committed suicide. Karl Dönitz became leader of the German government and quickly dispatched the German High Command to travel to Reims, France, to sign an unconditional surrender with the Allies. Field Marshal Jodl surrendered unconditionally on 7 May. The Western Allies celebrated "V-E Day" on 8 May and the Soviet Union "Victory Day" on 9 May.
U.S. capture of islands such as Iwo Jima and Okinawa brought the Japanese homeland within range of naval and air attack. Amongst dozens of other cities, Tokyo was firebombed, and on the initial attack alone, upwards of 90,000 people died as the fire raced unchecked through the city. The high loss of life was attributed to the dense living conditions around production centres and the wood and paper residential construction common to that period. In addition, the ports and major waterways of Japan were extensively mined by air in Operation Starvation which seriously disrupted the logistics of the island nation. Later on 6 August 1945, the B-29 "Enola Gay", piloted by Col. Paul Tibbets, dropped an atomic bomb (Little Boy) on Hiroshima, effectively destroying it. On 8 August 1945, the Soviet Union declared war on Japan, as had been agreed to at Yalta, and launched a large-scale invasion of Japanese occupied Manchuria (Operation August Storm). On 9 August, the B-29 "Bock(i)s Car", piloted by Maj. Charles Sweeney, dropped an atomic bomb (Fat Man) on Nagasaki. The combination of the use of atomic weapons and the new inclusion of the Soviet Union in the war were both highly responsible for the surrender of Japan. The Japanese surrendered on 15 August 1945, signing official surrender papers on 2 September 1945, aboard USS Missouri in Tokyo Bay. Japan(i)s surrender to the United States did not fully end the war, however, because Japan and the Soviet Union never signed a peace agreement. In the last days of the armed conflict, the Soviet Union occupied the southern Kuril Islands, an area previously held by Japan and claimed by the Soviets. Multiple efforts  to bring to a peace agreement, and officially end the war, have as yet not succeeded.
Main article: Resistance during World War II
Resistance during World War II occurred in every occupied country by a variety of means like guerrilla warfare, sabotage, propaganda, disinformation, hiding refugees and aiding the other side (like helping stranded pilots).
Among the most notable resistance movements were the French Maquis, the Polish Home Army, and the Yugoslav Partisans. For an impression of resistance organisation and activities in a small Dutch town see Valkenburg resistance.
Many countries had resistance movements dedicated to fighting the Axis invaders, and Germany itself also had an anti-Nazi movement. Although mainland Britain did not suffer invasion in World War II, the British made preparations for a British resistance movement, called the Auxiliary Units, in the event of a German invasion. Various organizations were also formed to establish foreign resistance cells or support existing resistance movements, like the British SOE and the American OSS (the forerunner of the CIA).