Rick Santorum identifies  a loss of nerve as the cause of the downfall of the British Empire:
“If you look at every European country that has had world domination, a world presence, from the French to the British — 100 years ago, the sun didn’t set on the British Empire,” Santorum said at an appearance in Sioux City, Iowa. “If you look at that empire today — why? Because they lost heart and faith in their heart in themselves and in their mission, who they were and what values they wanted to spread around the world. Not just for the betterment of the world, but safety and security and the benefit of their country.”
Yes, it couldn’t have had anything to do with two exhausting global conflicts that cost the lives of millions of British subjects, or the financial ruin of Britain that followed these conflicts. The British just “lost heart and faith in their heart in themselves and in their mission.” Obviously, the only thing needed to maintain “world domination” is self-confidence and resolve.