 Complete the following phrase:  In April 1915 the Admiralty requisitioned Arlanza and her A-series sisters , Andes and for conversion into armed merchant cruisers. Arlanza was armed with six guns, and commissioned at Birkenhead on 24 April 1915 into the 10th Cruiser Squadron. Andes and Alcantara were also commissioned into the 10th Cruiser Squadron, which joined the Northern Patrol that was part of the First World War 