Tower Hill Memorial, London

Standing on the south side of the gardens of Trinity Square, London, close to the Tower of London is the Tower Hill Memorial. It commemorates the men of the Merchant Navy and Fishing Fleets who have no grave but the sea. More than 50,700 Commonwealth merchant seamen lost their lives in the two world wars. The Tower Hill Memorial commemorates more than 35,800 casualties who have no known grave. In the First World War, the civilian navy's duty was to be the supply service of the Royal Navy, to transport troops and supplies to the armies, to transport raw materials to overseas munitions factories and munitions from those factories, to maintain, on a reduced scale, the ordinary import and export trade, to supply food to the home country and - in spite of greatly enlarged risks and responsibilities - to provide both personnel and ships to supplement the existing resources of the Royal Navy. Losses of vessels were high from the outset, but had peaked in 1917 when in January the German government announced the adoption of "unrestricted submarine warfare". The subsequent preventative measures introduced by the Ministry of Shipping - including the setting up of the convoy system where warships were used to escort merchant vessels - led to a decrease in losses but by the end of the war, 3,305 merchant ships had been lost with a total of 17,000 lives.