The Bruces advanced on Dublin (1316). A short time before, Edward Bruce had been crowned King of Ireland at Dundalk, and thinking the time had come for the expulsion of the English, he invited his brother Robert to his assistance. The King of Scotland landed in Ireland with a select body of troops, and, being joined by his brother, marched to besiege Dublin with 20,000 men. The first exploit on approaching the city was the taking of Castleknock. It could not be expected that the old fortress, long deemed impregnable, could long hold out against the hero of Bannockburn. Bruce entered, making Hugh Tyrrell prisoner, and fixed there his headquarters.