The St. Vincent-class battleships consisted of three ships of the Royal Navy laid down in 1908, and completed between May 1909 and April 1910. They were St. Vincent, Collingwood, and Vanguard. Vanguard was destroyed in an ammunition explosion, probably due to bagged cordite. Visually, they were very difficult to distinguish from the Bellerophons. The major innovation in this class was the adoption of longer 50 calibre main armament, increased from the 45 calibre fitted to previous classes.