In an attempt to lure out and destroy a portion of the Grand Fleet, the High Seas Fleet, composed of 16 dreadnoughts, 6 pre-dreadnoughts, and supporting ships, departed the Jade Bight early on the morning of 31 May. The fleet sailed in concert with Rear Admiral Franz von Hipper's 5 battlecruisers. The Royal Navy's Room 40 had intercepted and decrypted German radio traffic containing plans of the operation. In response the Admiralty ordered the Grand Fleet, totalling some 28 dreadnoughts and 9 battlecruisers, to sortie the night before to cut off and destroy the High Seas Fleet.