Like Gallipoli?
Gallipoli was such a horror show it's amazing that Churchill was trusted with anything after that.
The Royal Navy command on the scene was equally responsible for not executing the plan in an aggressive fashion. Due to their dilatory behavior the element of surprise was lost giving the Turks time to prepare defenses. Admiral Sackville Carden had a mental breakdown which caused delay and confusion. One ship hit a mine and sank. A fatal flaw was that the minesweepers were under civilian control and refused to clear the channel while operating under fire of the shore batteries.
It wasn’t a hair-brained idea. The execution was the problem. See Martin Gilbert’s biography of Churchill.