Robert Campbell, 1914

In a remarkable example of wartime honesty, Capt Robert Campbell, 29, kept his promise to the Kaiser by returning to the German prison, a historian has discovered. The soldier promised to return to POW camp after a visit with dying Mom.

Capt Campbell had languished in the Magdeburg prisoner of war camp for two years when he received word that his mother, Louise Campbell, had cancer and was close to death.

He wrote to Kaiser Wilhelm II, begging to be allowed home to visit her one final time.

And incredibly, the German leader granted his request, allowing him two weeks leave, including two days traveling each way by boat and train, as long as he returned.

The only bond he placed on him was Capt Campbell's “word” as an Army officer.

The young soldier returned to his family home in Gravesend, Kent, in December 1916 and spent time with his mother before returning to the camp, where he was held until the war ended in 1918.