stylistic:style_transfer
Anglo-Soviet invasion and deposition of his father Reza Shah

Meanwhile, in the midst of World War II in 1941, Nazi Germany began Operation Barbarossa and invaded the Soviet Union, breaking the Molotov–Ribbentrop Pact. This had a major impact on Iran, which had declared neutrality in the conflict. In the summer of 1941, Soviet and British diplomats passed on numerous messages warning that they regarded the presence of Germans administering the Iranian state railroads as a threat, implying war if the Germans were not dismissed. Britain wished to ship arms to the Soviet Union via Iranian railroads, and statements from the German managers of the Iranian railroads that they would not cooperate made both the Soviets and Brits insistent that the Germans Reza Khan had hired had to be sacked at once. As his father's closest advisor, the Crown Prince Mohammad Reza did not see fit to raise the issue of a possible Anglo-Soviet invasion of Iran, blithely assuring his father that nothing would happen. The Iranian-American historian Abbas Milani wrote about the relationship between the Reza Khan and the Crown Prince at the time, noting, "As his father's now constant companion, the two men consulted on virtually every decision".

Later that year, British and Soviet forces occupied Iran in a military invasion, forcing Reza Shah to abdicate. On 25 August 1941, British and Australian naval forces attacked the Persian Gulf while the Soviet Union conducted a land invasion from the north. On the second day of the invasion, with the Soviet air force bombing Tehran, Mohammad Reza was shocked to see the Iranian military simply collapse, with thousands of terrified officers and men all over Tehran taking off their uniforms in order to desert and run away, despite having not yet seen combat. Reflecting the panic, a group of senior Iranian generals called the Crown Prince to receive his blessing to hold a meeting to discuss how best to surrender. When Reza Khan learned of the meeting, he flew into a rage and attacked one of his generals, Ahmad Nakhjavan, striking him with his riding crop, tearing off his medals, and nearly personally executing him before his son persuaded him to have the general court-martialed instead. The collapse of the Iranian military that his father had worked so hard to build humiliated his son, who vowed that he would never see Iran defeated like that again, foreshadowing the future Shah's later obsession with military spending.