February 23 is the 54th day of the year in the Gregorian calendar. There are 311 days remaining until the end of the year (312 in leap years).

• 1455 – Traditional date for the publication of the Gutenberg Bible, the first Western book printed with movable type.

• 1739 – Richard Palmer is identified at York Castle, by his former schoolteacher, as the outlaw Dick Turpin.

• 1836 – The Battle of the Alamo begins in San Antonio, Texas.

• 1854 – The official independence of the Orange Free State is declared.

• 1861 – President-elect Abraham Lincoln arrives secretly in Washington, D.C., after the thwarting of an alleged assassination plot in Baltimore, Maryland.

• 1896 – The Tootsie Roll is invented.

• 1903 – Cuba leases Guantánamo Bay to the United States "in perpetuity".

• 1941 – Plutonium is first produced and isolated by Dr. Glenn T. Seaborg.

• 1945 – World War II: During the Battle of Iwo Jima, a group of United States Marines and a commonly forgotten U.S. Navy Corpsman, reach the top of Mount Suribachi on the island and are photographed raising the American flag.

• 1991 – Gulf War: Ground troops cross the Saudi Arabian border and enter Iraq, thus beginning the ground phase of the war.

• 1998 – Osama bin Laden publishes a fatwa declaring jihad against all Jews and "Crusaders"; the latter term is commonly interpreted to refer to the people of Europe and the United States.

• 1999 – Kurdish rebel leader Abdullah Öcalan is charged with treason in Ankara, Turkey.

• 2008 – A United States Air Force B-2 Spirit crashes on Guam. It is the first operational loss of a B-2.