Conversation so far:
What was the Battle of Hunayn?
In the Battle of Hunayn as the Muslim army passed through the valley of Hunayn some eleven miles north east of Mecca.
What did they do when the reached there?
Taken unaware the advance guard of the Muslim army fled in panic.
Then what did they do?
Under the instructions of Muhammad, Abbas shouted at the top of his voice "O Muslims come to the Prophet of Allah".

Question: When did the battle happen?
Self-contained rewrite: When did the Battle of Hunayn happen?