Short answers, pulled from the story.
The Hungarian Revolution of 1956 was caused by severe repression under Mátyás Rákosi, economic hardship with workers' disposable income dropping to two-thirds of its 1938 level, and political oppression enforced by the State Protection Authority known as ÁVH. Widespread shortages of bread, sugar, flour, and meat combined with forced industrialization led intellectuals to criticize the regime openly by 1955.
The Hungarian Revolution of 1956 began on the 23rd of October 1956 when approximately 20,000 people gathered at Petőfi Square in Budapest. The fighting concluded across most districts by the 9th of November 1956 after Soviet forces launched Operation Whirlwind on the 4th of November 1956.
Hungarian casualties totaled approximately 2,500 dead and 20,000 wounded during the conflict. On the Soviet side, 699 men were killed, 1,450 wounded, and 51 missing in action while fighting against insurgents in Budapest's eighth and ninth districts.
Marshal Ivan Konev commanded the Soviet operation known as Operation Whirlwind which invaded Hungary with seventeen divisions totaling over 200,000 troops. The Soviet armies deployed T-34-85 medium tanks, IS-3 heavy tanks, and BTR-152 armored personnel carriers to suppress the uprising.
Western powers failed to intervene because the concurrent Suez Crisis prevented effective criticism of Moscow and an Army study recommended against military intervention. Eisenhower's administration avoided direct confrontation fearing nuclear war with the USSR while secret National Security Council policies encouraged only psychological warfare.