Who was the first U.S. vice president to officially become acting president when the real president was incapable of performing his duties?

Believe it or not, George Bush was the first U.S. vice president to officially become acting president when the real president was incapable of performing his duties.

On July 13, 1985, while Reagan was having a tumor removed from his colon, he transferred presidential power to his vice president, George Bush.

Officially, the switch occurred at 11:28 A.M.

Eight hours later, power was transferred back.