Ismaili History 331 - Tabuk Expedition
With the conquest of Mecca, Islam marched with galloping speed throughout the length and breath of Arabia. The neighbouring Christian states, especially the Roman empire, were watching this unprecedented, triumphant march with a great concern and anxiety.
The fate of the Muslims in the battle of Mauta also emboldened the Arabs and Romans of the frontier regions to enhance their mischief-mongering towards the Muslims. Thus, to restore the loss of prestige and to teach lesson, Muhammad marched with an army of thirty thousand from Medina to Tabuk, a well known place about midway between Medina and Damascus. He on that very occasion, appointed Ali as his caliph in Medina, and as a result, Ali did not take part in the battle of Tabuk. In the mid-Rajab, 9/late October, 630, the Muslims set out for Tabuk. This was the largest army that had ever mustered under the command of Muhammad. The army drawn up for the battle of Tabuk, known as the Jaish al-Usrah (the army of difficulty). So called because in the first place the journey had to be undertaken in the scortching heat of the summer and secondly, it was the time of reaping the harvest and ripening of fruit which made it very difficult to proceed.
Reaching the field of Tabuk, Muhammad encamped his army, where he came to know that the Romans in Jordan had withdrawn to Damascus, and dared not to come to arms with the Muslims, and therefore, Muhammad returned to Medina after a couple of days. This was the last campaign commanded by Muhammad.