Retreating after the Battle of Ctesiphon, the British 6th Indian Division was closely pursued by Ottoman forces. Their commander, Major-General Townshend, decided to break their flight at Küt and wait for British relief forces to arrive. The town was easily defensible, being fortified and surrounded on three sides by a bend in the River Tigris. Initially, besieged forces had plentiful provisions and winter flooding forced the encircling Ottoman lines back. However, the relief operation met with a series of crushing reverses. Each attempt was repulsed by the now reinforced, and well entrenched, besieging army, costing 30,000 Allied casualties. The final effort was abandoned near Sonnaiyat, some 10 miles (16 km) from Küt, on 21 April. Attempts to supply the besieged forces by air were largely ineffective and, by April, they were nearing starvation. Any hope of relief gone, Townshend surrendered his remaining army of 9,000 men on 29 April.