2020 – The Dow Jones Industrial Average falls by 2,997.10, the single largest point drop in history and the second-largest percentage drop ever at 12.93%, an even greater crash than Black Monday (1929). This follows the U.S. Federal Reserve announcing that it will cut its target interest rate to 0–0.25%.

2014 – Crimea votes in a controversial referendum to secede from Ukraine to join Russia.

1995 – Mississippi formally ratifies the Thirteenth Amendment to the United States Constitution, becoming the last state to approve the abolition of slavery. The Thirteenth Amendment was officially ratified in 1865.

1939 – From Prague Castle, Hitler proclaims Bohemia and Moravia a German protectorate.

1935 – Adolf Hitler orders Germany to rearm itself in violation of the Treaty of Versailles. Conscription is reintroduced to form the Wehrmacht.

1926 – History of Rocketry: Robert Goddard launches the first liquid-fueled rocket, at Auburn, Massachusetts.

44 BC – The assassination of Julius Caesar, the dictator of the Roman Republic, by a group of senators takes place on the Ides of March.

1982 – The South African government bombs the headquarters of the African National Congress in London.

1961 – A USAF B-52 bomber carrying nuclear weapons crashes near Yuba City, California.

1942 – Anne Miller becomes the first American patient to be treated with penicillin, under the care of Orvan Hess and John Bumstead.

1903 – Pelican Island National Wildlife Refuge, the first national wildlife refuge in the US, is established by President Theodore Roosevelt.

2020 – President Donald Trump declares the COVID-19 pandemic to be a national emergency in the United States.

2020 – The United States suspends travel from Europe due to the COVID-19 pandemic.

1993 – North Korea announces that it will withdraw from the Treaty on the Non-Proliferation of Nuclear Weapons and refuses to allow inspectors access to its nuclear sites.

1989 – Sir Tim Berners-Lee submits his proposal to CERN for an information management system, which subsequently develops into the World Wide Web.

1933 – Great Depression: Franklin D. Roosevelt addresses the nation for the first time as President of the United States. This is also the first of his "fireside chats".

1938 - Germany annexes Austria.

2020 – The World Health Organization (WHO) declares the COVID-19 virus epidemic a pandemic.

2020 – Giuseppe Conte, Prime Minister of Italy, announces in a televised address and signs the decree imposing the first nationwide COVID-19 lockdown in the world.