Final answer:
Andrew Johnson served as the 17th President of the United States from 1865 to 1869. He was known for his role in Reconstruction after the Civil War and for being the first U.S. president to be impeached.
Step-by-step explanation:
Andrew Johnson served as the 17th President of the United States. He assumed the presidency on April 15, 1865, following the assassination of Abraham Lincoln, and served until March 4, 1869. He is known for his role in Reconstruction after the Civil War and for being the first U.S. president to be impeached by the House of Representatives. However, he was narrowly acquitted by the Senate.