Who was appointed as the first commander-in-chief of the Muslim army for the expedition of Mu’tah in 8 AH?

Explanation

For the Battle of Mu’tah (8 AH), Prophet Muhammad (PBUH) designated a chain of command: Hazrat Zayd ibn Harithah (RA) was appointed first commander. If martyred, Hazrat Ja’far ibn Abi Talib (RA) was to take command, followed by Hazrat Abdullah ibn Rawahah (RA). After all three achieved martyrdom, Hazrat Khalid ibn al-Walid (RA) took command and executed a tactical retreat. Zayd (RA) is also the only Sahabi mentioned by name in the Quran (Surah Al-Ahzab).