Battle of Khandaq

The Battle of Khandaq (627 CE), also called the Battle of the Trench, was a twenty-seven-day siege of Medina by a coalition of some ten thousand Quraysh and allied tribes. On Salman al-Farsi's advice the Muslims dug a defensive trench, and the coalition withdrew without a decisive battle.

Salman al-Farsi was a Persian who left Zoroastrianism for Christianity, was sold into slavery on his way to Arabia, and became a Companion of Prophet Muhammad. His own first-person account of that search survives, and he is credited in the biographical sources with proposing the trench at Khandaq.