How the Korean War Changed the Way the U.S. Goes to Battle

In the Cold War, North Korean Communists invaded South Korea. President Truman’s decision to intervene had consequences that shape the world today.

During the Cold War, President Harry Truman watched with alarm as North Korean Communists invaded South Korea. Truman believed the U.S. had to intervene. But his decision to rush troops to stop the Communist advance had unintended consequences that shape the world today.

For teachers
  • Producer: Joseph Hogan
  • Sr. Producer: Kit R. Roane
  • Editor: Cullen Golden

For Educators


This six-minute video provides students with an introduction to the Korean War, including its context within the Cold War, and the hardships faced by American soldiers on the battlefield. Focusing on President Truman’s decision not to seek a formal Declaration of War from Congress, the video also sets up a discussion about the evolution and expansion of presidential war powers.

This video was featured in an online class on The Cold War in partnership with The Gilder Lehrman Institute’s History School and Joe Welch, a 2018 Gilder Lehrman National History Teacher of the Year and Master Teacher.

Lesson Plan 1: The Korean War

Students will learn how President Harry Truman’s use of presidential power during the Korean War continues to influence U.S. foreign policy and military engagements around the world today.


Students will learn about:

  • How North Korean’s invasion of South Korea in 1950 played into U.S. fears that the Soviet Union and Communist China were intent upon spreading communism across the globe.
  • Why President Harry Truman responded to the invasion by framing America’s participation in the war as a United Nations “police action” rather than asking Congress to issue a formal declaration of war.
  • How Truman’s decision to avoid the Constitutional process for declaring war through Congress has affected American politics and foreign policy ever since.
Essential questions
  • Why didn’t President Truman seek a formal Declaration of War from Congress?
  • How did Truman legally justify sending troops to Korea without a formal Declaration of War?
  • How did China’s decision to send troops to Korea affect the outcome of the war?
  • Why did some members of Congress believe that Truman should have first consulted them and sought a declaration of war before sending troops into harm’s way in Korea?
  • How has Truman’s decision not to seek a formal Declaration of War from Congress affected the power of an American president to wage war and commit troops to battle?
  • Common Core State Standards
    • CCSS.ELA.LITERACY.RI.11-12.3:Analyze a complex set of ideas or sequences of events and explain how specific individuals, ideas, or events interact or develop over the course of a text.
    • CCSS.ELA.LITERACY.RH.11-12.7:Integrate and evaluate multiple sources of information presented in diverse formats and media (e.g., visually, quantitatively, as well as in words) in order to address a question or solve a problem.
  • National Council for the Social Studies C3 Framework
    • D2.His.14.9-12.Analyze multiple and complex causes and effect of events in the past.
    • D2.Civ.13.9-12.Evaluate public policies in terms of intended and unintended outcomes, and related consequences.
  • AP U.S. History
    • Period 8: 1945-1980
    • Topic 8.2: The Cold War from 1945 to 1980

      Skill 3.A: Identify and describe a claim and/or argument in a non-text-based source.

      Theme 6: America in the World (WOR).

  • AP Human Geography
    • Unit 4: Political Patterns & Processes