April 19

1529 – Accepted by many as the beginning of the Protestant Reformation, a group of rulers and independent cities protests the reinstatement of the Edict of Worms after the Second Diet of Speyer bans Lutheranism.

1775 – At Lexington and Concord, Massachusetts militia confront British troops marching to confiscate arms and military supplies.

1782 – John Adams secures Dutch recognition of the United States as an independent government. The house which he had purchased in The Hague becomes the first American embassy.

1818 – French physicist Augustin Fresnel signs his preliminary “Note on the Theory of Diffraction” . The document ends with a set of mathematical equations now called the Fresnel Integrals which leads to the development of the Fresnel lens, a flat, thin, compact, more powerful and less expensive refractive lens.

1861 –In Baltimore, Maryland, a group of pro-Secession protesters attacks U.S. Army troops marching through the city.

1943 – In Warsaw, Poland, the Ghetto Uprising begins, after German troops enter the Warsaw Ghetto to round up the remaining Jews and holding off the Nazi force for nearly a month using only a handful of weapons.

1956 – Actress Grace Kelly marries Prince Rainier of Monaco.

1971 – Charles Manson is sentenced to death, which is later commuted to life imprisonment, for conspiracy in the Tate–LaBianca murders.

1985 – 200 ATF and FBI agents lay siege to the compound of the survivalist group The Covenant, The Sword, and the Arm of the Lord near Three Brothers, Arkansas

1989 – Aboard the USS Iowa, an explosion of the center 16 inch gun in Gun Turret 2, kills all 47 sailors in the turret.

1993 – The 51 day siege by the FBI of the Branch Davidian compound in Waco, Texas, ends when a fire breaks out. 76 Davidians, including 18 children under the age of 10, die in the fire.

1995 –  In retaliation for the siege of the Branch Davidian compound, the Alfred P. Murrah Federal Building in Oklahoma City, is bombed, killing 168 people, including 19 children under the age of 6.

2013 – In the city suburb of Watertown, Boston Marathon bombing suspect Tamerlan Tsarnaev is killed in a shootout with police. His brother Dzhokhar is later captured hiding in a boat inside a backyard.

2021 – The Ingenuity helicopter flies off NASA’s Perseverance Mars rover becomes the first aircraft to achieve powered independent flight on another planet.