I wrongly said First Sea Lord.
I should have said First Lord of the Admiralty.
It was in that post that he cocked up the war planning for the disastrous Norway campaign. It had also been in that post that he initiated the disastrous Dardanelles campaign which was another omnishambles.
To his credit, on the other hand, it was as First Lord of the Admiralty that he promoted the development of what we now call tanks on the naval budget. They were regarded as a naval thing because they were called landships. The word tank was a ruse to confuse German Intelligence with the cover story that the development work was on mobile water tanks for use in the North African desert.