This is an easier one. The third battle between the muslims (Mediina) & Quraish (Mecca) is called 'battle of ditch'. This is on account of the fact that the Meccans were not able to enter Medina on account of a ditch arround it.

Whose ides was it to dig a grave arround Medina?
How did the battle end & who won ?

Following the idea of Salman al-Faras, Muhammad ordered the trenches to be dug in that open end of the city, and thus it is called the battle of Ditch (khandaq).

The Muslims won, One night the wild wind terribly rose and soon gathered into a storm. It uprooted their tents, scattered their provisions, scared their mounts, and, what with the dark and unusual cold, spread so much terror and confusion in the camp that when the day dawned, the siege had been lifted and the invaders withdrew from the field. Each man carried as little as his camel, horse, or shoulders could bear and began to move while the storm continued to rage. The encounter at the battle of Ditch was the last time that the town of Medina ever faced an invader.

Thats the idea was from Salman the Pharse (persian).

Muslims while not allowing the meccans/pagans to enter Medina, at the end were helped by a storm which uprooted the camps of the meccans/pagans & they withdrew from their seige.

All praises are for God. Peace.