Answer:
Joseph Stalin was responsible for the breakdown of the "grand alliance" that had defeated Hitler and his allies and had won World War II.
Step-by-step explanation:
Joseph Vissarionovich Stalin born on the 18th of December 1878 was the General Secretary of the Communist party of the Soviet Union and he studied Adolf Hitler, including reading Mein Kampf and from it knew of Hitler's motives for destroying the Soviet Union.
Hence, causing the breakdown of the "grand alliance" that had defeated Hitler and his allies and had won World War II.