It did indeed ruin him for many years, and he carried that around, no doubt.
But thank GOD he was the man he was. He was so stubborn that he refused to let that define him.
Many a lesser man has worn an albatross like that around his neck, helped by the bottle all the way to the grave.
But he did think about it, in much the same way Halsey did think on his performance at Leyte Gulf and in Typhoon Cobra in WWII.
Churchill and Halsey, both great men, with flaws. I find them both fascinating including their flaws.
“I am the victim of a political intrigue,” he lamented to a friend. “I am finished!” Displaying the steely determination that would serve him well in World War II, however, the marginalized Churchill did not slink from the fight. In November 1915, the statesman turned soldier. Churchill resigned from the government, picked up a gun and headed to the front lines in France as an infantry officer with the Royal Scots Fusiliers. After several brushes with death, he returned to politics in 1917 as the munitions minister in a new coalition government headed by Liberal Prime Minister David Lloyd George.
Churchill, however, remained haunted by Gallipoli for decades. “Remember the Dardanelles,” his political opponents taunted when he stood up to speak in the House of Commons. When running for Parliament in 1923, hecklers called out, “What about the Dardanelles?” The “British Bulldog” embraced Gallipoli as a brilliant failure. “The Dardanelles might have saved millions of lives. Don’t imagine I am running away from the Dardanelles. I glory in it,” he responded.
Although many shared the views of a political insider who in 1931 speculated that “the ghosts of Gallipoli will always rise up to damn him anew,” Churchill became prime minister in 1940 with Britain once again embroiled in war. Upon taking office, he wrote, “All my past life had been a preparation for this hour and for this trial.” That included Gallipoli.
https://www.history.com/news/winston-churchills-world-war-disaster