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 24–25 April. This time, the battlecruisers bombarded Yarmouth and Lowestoft. During this operation, the battlecruiser was damaged by a British mine and had to return to port prematurely. Visibility was poor, so the operation was quickly called off before the British fleet could intervene and inflict further losses. "Hessen" relieved "Preussen" in the straits on 4 May, remaining there until the 20th. She returned to the rest of the squadron at Altenbruch on 23 May to begin preparing for the next major fleet operation.