The grandfather and grand-mom at the movie are Nuri Bilge Ceylan's (director) father and mother in real life.
First part of the unofficial "Provincial Trilogy" with Mayis Sikintisi (1999) and Uzak (2002).
The battle described by the grandfather, known to the British as "Defence of Kut Al Amara", took place between December 1915 and April 1916. British troops were besieged in the town of Kut and eventually had to surrender when relief forces could not reach them. However, the British commander did not commit suicide as the grandfather says, but was imprisoned for the remainder of the war. It is possible that the grandfather was captured at the Second Battle of Kut, won by the British forces.