Complex sentence: After recovering, he returns to the hidden seminary, the Soviets start their Vistula-Oder Offensive in early 1945 and the Communist Provisional Government of National Unity is formed on June 28.
Split into simpler sentences: After recovering, he returns to the hidden seminary. In 1945, the Soviets start their Vistula-Oder Offensive and the Communist Provisional Government of National Unity is formed on June 28.