The Battle of Nahr-al-Kalek was fought in February 1917, shortly after the British recapture of Kut. The British victory destroyed the Turkish river forces on the Tigris River, leaving the British in control of the waterway.
The Royal Navy gunboats Mantis, Moth, and Tarantula were pursuing the retreating Turkish force from Kut when they inadvertently ran ahead of their own ground forces.
The British gunboats found themselves under fire from four Turkish vessels, including the originally British monitor Firefly.
In the ensuing gunnery battle, the British gunboats routed the Turks, destroying all three Turkish-built ships and successfully recapturing Firefly.
The British also secured several hundred prisoners from Turkish infantry along the shore.
If the Royal Navy vessels had not been some distance ahead of their own infantry, they could have inflicted even more damage on the Turks.