Helga was an armed ship, which sailed from Dún Laoghaire (then Kingstown) to shell the rebel garrison at Boland’s mill on Tuesday 25th April 1916. From the river Liffey, it fired over the loop line railway bridge at Liberty Hall on the following day. The blue ensign from the vessel displays the Union Jack in the top left hand corner and the Irish harp with eight white strings, surrounded by a white belt with green shamrocks. A plain blue ensign was flown on Royal research ships and other ships in British public service. It also formed the basis for many flags of British colonies, for example Malta, Nigeria and Hong Kong. Helga was used in Ireland, hence the blue ensign with an Irish emblem (harp and shamrock) was used on the ship. Helga was originally built for the Department of Agriculture in 1908 in Dublin Dockyard and used as a marine research ship. During the First World War, it was used by the British Admiralty as an escort vessel and on anti-submarine patrol. When it sailed up the river Liffey in 1916, Helga was armed with a twelve-pounder coastal defence gun and a ‘pom-pom’, a smaller three-pounder naval gun. Contrary to popular myth, most of the damage in the city, however, was not caused by ammunition fired from Helga.