A CANNON has been fired to mark the 100th anniversary of the first shot fired at sea by the Royal Navy in the First World War.

The gun salute was held at the Royal Yacht Squadron in Cowes, Isle of Wight, and included a sail past by the patrol vessel HMS Mersey.

A single cannon was fired before a one-minute silence was held to remember those who served in defence of the nation before a further cannon shot was fired to bring the remembrance event to a close.

The event was held to mark the first shot at sea which was fired from the gun of HMS Lance in the North Sea on August 5 1914.

The gun is now a permanent exhibit in the HMS - Hear My Story gallery at the National Museum of the Royal Navy (NMRN) in Portsmouth Historic Dockyard.

This year's Britannia Cup race, run by the Royal Yacht Squadron during Aberdeen Asset Management Cowes Week, is also being dedicated to the centenary of the Great War at sea.

Professor Dominic Tweddle, NMRN's director-general, said: ''It is commonly believed that the First World War was fought entirely in the trenches; however, our naval forces were engaged in battle across the world.

''Some 43,244 naval personnel lost their lives during the war. That single shot from HMS Lance signified the start of a campaign at sea that came at considerable human cost.

''Cowes Week is acknowledged the world over as one of the most prestigious sailing events and we are touched that the organisers and the Royal Navy join with us in marking this sombre and thought-provoking centenary in a time-honoured fashion.''

The Royal Yacht Squadron played an important supporting role during the First World War. Members who owned large steam yachts were quick to offer their vessels to the Admiralty when war was declared and 38 were requisitioned.

Once an owner had agreed to lend his yacht for the duration of the war, their vessel was taken to a naval dockyard - usually Portsmouth - to be fitted out for war service.

Valuable items were removed and replaced by guns, the decks were strengthened to take them and they were painted grey.

Of the 38 yachts, four were sunk by mines, one was lost in a collision, one was wrecked while chasing a submarine in heavy weather and all the others survived the war.

Four others yachts served as hospital ships and the club's headquarters - the castle at Cowes - was opened up to convalescent naval officers.