Final answer:
Winston Churchill was the leader who disapproved of the policy of appeasement and later led Britain through World War II after replacing Neville Chamberlain as Prime Minister.
Step-by-step explanation:
The leader who disapproved of the policy of appeasement was Winston Churchill. He was a lifelong British politician who clearly saw the dangers of Adolf Hitler's rise to power in Germany. Unlike his predecessor, Neville Chamberlain, who along with French and Italian leaders allowed Germany to annex parts of Czechoslovakia in the hope of avoiding war, Churchill believed that such concessions would only encourage Hitler's aggression. After Chamberlain's resignation in 1940, Churchill became Prime Minister and led Britain through World War II, emphasizing determination and resistance rather than appeasement, famously stating he had nothing to offer but "blood, toil, tears, and sweat" in the fight against Nazi Germany.