 Complete the following phrase:  On 5 April, the Admiralstab Admiralty Staff determined that ships of II Squadron should be periodically sent to guard the Danish straits. Hessen performed this duty from 10 to 20 April, when she was replaced by . Hessen returned to the North Sea, and was present for another attack on the British coast on 2425 April. This time, the battlecruisers 