Aulus Vitellius was Roman Emperor for eight months, from 19 April to 20 December AD 69. Vitellius was proclaimed emperor following the quick succession of the previous emperors Galba and Otho, in a year of civil war known as the Year of the Four Emperors. His claim to the throne was soon challenged by legions stationed in the eastern provinces, who proclaimed their commander Vespasian emperor instead. War ensued, leading to a crushing defeat for Vitellius at the Second Battle of Bedriacum in northern Italy. Once he realized his support was wavering, Vitellius prepared to abdicate in favor of Vespasian. He was not allowed to do so by his supporters, resulting in a brutal battle for Rome between Vitellius' forces and the armies of Vespasian. He was executed in Rome by Vespasian's soldiers on 20 December 69.

As States sent Union regiments south, on April 19, Baltimore mobs in control of the rail links attacked Union troops who were changing trains. Local leaders' groups later burned critical rail bridges to the capital and the Army responded by arresting local Maryland officials. Lincoln suspended the writ of habeas corpus where needed for the security of troops trying to reach Washington. John Merryman, one Maryland official hindering the U.S. troop movements, petitioned Supreme Court Chief Justice Roger B. Taney to issue a writ of habeas corpus. In June Taney, ruling only for the lower circuit court in ex parte Merryman, issued the writ which he felt could only be suspended by Congress. Lincoln persisted with the policy of suspension in select areas.

On 19 April 1906, Pierre Curie was killed in a road accident. Walking across the Rue Dauphine in heavy rain, he was struck by a horse-drawn vehicle and fell under its wheels, causing his skull to fracture. Curie was devastated by her husband's death.

In 1910 Ehrlich and Hata announced their discovery, which they called drug "606", at the Congress for Internal Medicine at Wiesbaden.

On 19 April 1915, Jevdet Bey demanded that the city of Van immediately furnish him 4,000 soldiers under the pretext of conscription. However, it was clear to the Armenian population that his goal was to massacre the able-bodied men of Van so that there would be no defenders. Jevdet Bey had already used his official writ in nearby villages, ostensibly to search for arms, but in fact to initiate wholesale massacres. The Armenians offered five hundred soldiers and exemption money for the rest in order to buy time, but Jevdet Bey accused the Armenians of "rebellion" and asserted his determination to "crush" it at any cost. "If the rebels fire a single shot", he declared, "I shall kill every Christian man, woman, and" (pointing to his knee) "every child, up to here".