Churchill did nothing wrong, I will not elaborate.
- Gallipoli was a good strategy. Knockout the Ottomans and secure some oil. Churchill got unlucky and faced one of the greatest commanders in history. The terrain was awful, but they had good reason to underestimate the Turks. They were comically incompetent and disorganized with the exception of Attaturk.
- Indian famines. You cannot blame one man for this as British rule and precolonial India setup a system where peasants paid rents to landlords who did not care about them. It was an export based economy that relied on imported rice. That rice being cutoff only happened after the British got basically their entire army in Asia destroyed at the Battle of Singapore. The army was well equipped and had alot of soldiers. It was just caught by surprise.
-France 1940. British and French were well prepared to hold the Germans back like in ww1. The politicians (including Chamberlain) did everything that could be reasonably be done. The commanders failed. Churchhill did a good job at salvaging the France debacle and not surrendering. Some here support a British surrender, but why surrender to somebody who has broken every agreement they have ever made?
-Strategic bombing. Pretty much every military historian I have read agrees that had it minimal impact on he war, but at the time they did not know that. Nobody could predict that the Germans would somehow increase production by moving factories into the forest. At the time they did predict that it would strengthen German resolve, but that was hardly the goal anyway. Regardless, this decision was the right call. The Germans had already been doing strategic bombing against the allies so there was literally no reason not to bomb them back.
-Italy. Dunno why this campaign gets so much hate. The allies were not ready for D-Day and had to do something. Italy was a place where they could practice for D-Day, use their naval supremacy to the fullest, and actually divert some units away from the Eastern Front.
- The British Empire. People love the British Empire, but it sucked. It cost the govt alot of money just to enrich a small few elites with stocks and properties across the empire. You can get the resources without owning the places.