The Post Office was responsible for mail sent to all theatres of war, including ships, and to prisoners of war. A special sorting office – the Home Depot – was built to deal with mail to the troops.

At the start of the war, mail for the Western Front was sorted into the army units in France. It was soon realised that it would be better to do this in Britain. The Post Office built the Home Depot in Regent's Park in London to use as a sorting office in December 1914. The volume of mail to be processed was so large that they constructed what was then the largest wooden building in the world.

The First World War was a global conflict requiring mail to be sent all over the world. The easiest way to transport it was by sea, but the dangers of enemy ships and mines meant that from 1915 to 1917 mail was transported to many of the war zones overland. In 1917 convoys were introduced to protect the ships and post was once again transported by sea.

The Post Office was responsible for sending mail to Royal Navy ships and to prisoners of war. A special section in London was given information on the locations of ships. People sending mail to the Navy addressed it to the ship's name, care of 'GPO London'. All countries involved in the war set up reciprocal agreements for the delivery of post to prisoners of war free of charge.

Once post, sent from the Home Depot, arrived overseas, it became the responsibility of the Army Post Office until it was delivered to the postal orderly of each unit. Despite the volume, the service was highly efficient – on average it took only two days for a letter from Britain to reach the Western Front (unless it was held up by the censor).

Illustrations

Bags of mail at the Home Depot, London

Photograph of men below deck on a ship

Soldiers sort mail on the Western Front

Wounded Indian troops writing a letter

Letter censored on board a ship

Special Royal Mail vehicle for Russia