In 1939, diplomatic relations between Egypt and Iran were upgraded to ambassadorial level, and Youssef Zulficar Pasha was appointed as Egypt's first ambassador in Tehran. In the same year, Princess Fawzia of Egypt, the sister of King Farouk I, married Mohammad Reza Pahlavi, the then crown prince (later shah) of Iran. The relationship between Iran and Egypt had fallen into open hostility under Gamal Abdul Nasser presidency. Following his death in 1970, President Sadat turned this around quickly into an open and cordial friendship. In 1971, Sadat addressed the Iranian parliament in Tehran in fluent Persian, describing the 2500-year-old historic connectivity between the two nations. Overnight, Egypt and Iran were turned from bitter enemies into fast friends. The relationship between Cairo and Tehran became so friendly that the Shah of Iran (Persia), Mohammad Reza Pahlavi, called Sadat his "dear brother." After the 1973 war with Israel, Iran assumed a leading role in cleaning up and reactivating the blocked Suez Canal with heavy investment. Iran also facilitated the withdrawal of Israel from the occupied Sinai Peninsula by promising to substitute with free Iranian oil the loss of the oil to the Israelis if they withdrew from the Egyptian oil wells in Western Sinai. All these added more to the personal friendship between Sadat and the Shah of Iran.