In 1648, the relatively brief Second English Civil War broke out, and Rupert informed the French King that he would be returning to King Charles’s service. The Parliamentary navy mutinied in favour of the King and sailed for Holland, providing the Royalists with a major fleet for the first time since the start of the civil conflict; Rupert joined the fleet under the command of the Duke of York, who assumed the rank of Lord High Admiral. Rupert argued that the fleet should be used to rescue the King, then being held prisoner on the Isle of Wight, while others advised sailing in support of the fighting in the north. The fleet itself rapidly lost discipline, with many vessels’ crews focussing on seizing local ships and cargoes. This underlined a major problem for the Royalists—the cost of maintaining the new fleet was well beyond their means. Discipline continued to deteriorate and Rupert had to intervene personally several times, including defusing one group of mutinous sailors by suddenly dangling the ringleader over the side of his vessel and threatening to drop him into the sea. Most of the fleet finally switched sides once more, returning to England in late 1648.