Conversation so far:
When did Ruhollah Khomeini return to Iran?
Ruhollah Khomeini returned to Iran on 1 February 1979
Why did Ruhollah Khomeini return to Iran?
Ruhollah Khomeini decided to return to Iran after Mohammad Reza Pahlavi, the Shah of Iran, fled on 16 January 1979.

Question: How'd he get back to Iran?
Self-contained rewrite: How'd Ruhollah Khomeini get back to Iran?