It was a shot across the bows that went down in history. On Tuesday, a century later to the minute, the first shot fired by the British Empire in World War I was remembered by thousands of people who gathered at a former military base.

Fired not in Europe or on the Gallipoli Peninsula but on the tip of Victoria’s Mornington Peninsula, the first Allied shot of World War I served as a warning to the German trading ship SS Pfalz, which was caught trying to flee Port Phillip Bay less than four hours after Britain declared war with Germany.

The first shot is sent across the bows of the German steamer Pfalz in 1914.

''That shot very clearly marked a moment in time where the old world changed and the new world manifested itself,’’ said chairman of the First Shot Committee Bernie Gaynor. ''After that shot, it was World War I, which led into World War II.’’

John Purdue, a sergeant with the army's Royal Australian Garrison Artillery, fired the shot at 12.45pm from Fort Nepean, near Portsea. On Tuesday, his grandchildren John Purdue, Carolyn Smyth and Louise Nicol were among the 4000-strong crowd, which included hundreds of school children.