The Uprising was the largest military effort by an occupied country during WWII. It began August 1 1944 and was crushed totally 63 days later.
It had been planned as part of Operation Tempest, the Polish plan to rise against the Germans as soon as they were to retreat from Poland--a plan begun in Sept. 1942. The plan was to take governmental control and re-establish a Polish army immediately in order to re-establish the rest of Polish civil and military organization. The Poles wanted the Allies to see that there was a Polish government and civil authorities. Poles felt highly pressured to do this quickly.
The immediate army to be formed was to be based on the pre-war Polish army, and the names of the divisions were to be used for the Home Army that was to form. The Uprising was to have 3 stages, first to take place nearest the Red Army, then to proceed into areas of less threat. Since diplomacy between the Polish government and the Soviet had been broken in 1943 (After Germans notified the Poles of a 1940 Soviet massacre of all [22 000] captive Polish officers) by Soviet Secret Police Stalin broke refused to answer and broke off relations), the Poles feared the Soviets would not liberate them as friends, and whose propaganda would brand them impotent or collaborationist.
In considering the importance of the Uprising, the Poles bore in mind that the Ukrainian Army had, between 1943 and 1944, in other regions of occupied Poland, ethnically cleansed those areas by official policy (to purge all non-Ukrainians from the future Ukrainian state of all male Poles ages 16-60 [though more women and children were killed than men]).
Prior to the Warsaw Uprisings, there had been other instances of Polish armed uprisings against the Germans, coordinating with the Red Army, but each time after victory the Red Army imprisoned them or forced them to convert to the Red Army or being sent to Soviet Labor Camps.
Besides the common enemy of Germany, the Poles and Russians were antagonistic, the Poles wanting to reinstate their government and pursue a democratic, Western-allied future and the Soviets wanted to install a communist government and make a satellite of Poland.
The occupying Germans had been preparing Warsaw to meet the uprising.
On the eve of the Uprising, the Red Army was approaching Warsaw, and from Soviet-controlled radio stations were calling for Poles to rise in arms"
"The Polish Army of Polish Patriots... calls on the thousands of brothers thirsting to fight, to smash the foe before he can recover from his defeat... Every Polish homestead must become a stronghold in the struggle against the invaders... Not a moment is to be lost."
"Fight the Germans! No doubt Warsaw already hears the guns of the battle which is soon to bring her liberation. [...] The Polish Army now entering Polish territory, trained in the Soviet Union, is now joined to the People's Army to form the Corps of the Polish Armed Forces, the armed arm of our nation in its struggle for independence. Its ranks will be joined tomorrow by the sons of Warsaw. They will all together, with the Allied Army pursue the enemy westwards, wipe out the Hitlerite vermin from Polish land and strike a mortal blow at the beast of Prussian Imperialism."
The Uprising was put off for days, and, although the Poles had prepared for a series of coordinated night attacks which would last a few days until the Red Army reinforced them, the Uprising was ordered in daylight and the Soviets waiting out the conflict from the other side of the river. In the important, establishing first days of the conflict, the separate Polish forces had varying degrees of successes, but managed to hold most of Warsaw, although not Castle Square, the police district, or the airport, and the Polish forces failed to link up.
The Germans retreated until they met up with reinforcements and a new General, after which they pursued an attack, and killing all civilians door-to-door behind their lines. The lines became more stable, and the Germans eventually won the conflict, forcing cornered Poles to flee. Those who did not escape were either shot or sent to concentration camps. The Poles signed the capitulation order Oct 2.
Germany sent the entire Warsaw population to a transit camp. Of 350 000 - 550 000 civilians, 90 000 were sent to labor camps, 60 000 to death and concentration camps, and the rest were shipped to various locations and released. Germany ordered the utter destruction of the remainder of the city.
The Red army and the Allies during the Uprising. After the Red Army fought its way to the Vistula River, the Kremlin ordered the army to halt and it deliberately (or, according some some historians, because they were simply unable to help) did not aid the Poles, and instead stayed put watching the German-Polish conflict zone, providing only sporadic artillery and air support. The Allies had provided assistance to the Poles by airlifts of supplies, but Stalin had not permitted them to use the airbases in Poland (requiring them to use England's and Italy's), calling the Poles as "a handful of criminals."
When the Soviets took Warsaw in January they were able to say they "liberated" Warsaw.
Stalin did not let the Polish government in exile return, instead installing his choice of Soviet-subservient government.