Was MacArthur wrong about strategy?

That remains debated militarily, but the firing was not really about whether his strategic instincts were correct. It was about a battlefield commander publicly organizing opposition to his civilian commander's declared policy, which the constitutional chain of command does not permit regardless of the merits of the underlying disagreement.

Did firing MacArthur hurt Truman politically?

Significantly and immediately. His approval rating dropped to some of the lowest levels recorded for a sitting president, and MacArthur received a far warmer public reception on returning home than Truman did for making the decision.

How is the decision viewed by historians today?

Most historians now regard it as a necessary, if politically costly, defense of the principle that military commanders answer to elected civilian leadership, a precedent that shaped how the chain of command has functioned in every conflict since.

politics · 1950 to 1951

Truman Fires MacArthur: The Cost of Enforcing the Chain of Command

General Douglas MacArthur was winning headlines and popular admiration while publicly contradicting his president's war strategy. Truman fired him anyway, and paid for it in the polls almost immediately.

Facts drawn from the Truman Presidential Library, the US Army Center of Military History, and Gallup's historical polling archive; interpretive framing is labeled as modeled analysis.

General Douglas MacArthur commanded United Nations forces in the Korean War, delivering a dramatic early success with the Inchon landing before Chinese forces entered the war and pushed UN troops back, escalating the conflict far beyond what Washington had planned for.

[VERIFIED] MacArthur repeatedly and publicly pushed for expanding the war into China and criticized the Truman administration's limited-war strategy, culminating in a March 1951 letter to a congressional leader that was read aloud on the floor of the House of Representatives, directly undercutting the administration's declared policy in public view.

Sources

[VERIFIED] MacArthur's public criticism of administration policy and the March 1951 letter Harry S. Truman Presidential Library and Museum, Truman and MacArthur
[VERIFIED] The Korean War timeline, including the Inchon landing and Chinese intervention US Army Center of Military History, Korean War chronology
[VERIFIED] Truman's approval rating fell to roughly 22 percent shortly after the dismissal Gallup, Presidential Approval Ratings, Historical Statistics and Trends