Documentary looking at the letters soldiers write, to be read only in the event of their death in conflict.
Featuring letters from the American Civil War, Allied forces in both world wars, and Japanese kamikaze pilots.
The programme also hears from veterans of the Falklands and Gulf wars, who wrote letters that never had to be sent or read.
Also focusing on the current conflicts in Iraq and Afghanistan, and featuring letters and the last blogs and poems from British and American soldiers.
Some have used their final words to criticise the wars, others to leave simple heartfelt messages of love for those left behind.
The programme also hears from a family whose son was killed in Afghanistan, and how his last letters are their sole comfort.