On 20 March 1811, Marie Louise gave birth to a baby boy, whom Napoleon made heir apparent and bestowed the title of King of Rome. His son never actually ruled the empire, but given his brief titular rule and cousin Louis-Napoléon's subsequent naming himself Napoléon III, historians often refer to him as Napoleon II.
In March 1920, Tomás Mac Curtain, the Sinn Féin Lord Mayor of Cork, was shot dead in front of his wife at his home, by men with blackened faces who were seen returning to the local police barracks. The jury at the inquest into his death returned a verdict of wilful murder against David Lloyd George (the British Prime Minister) and District Inspector Swanzy, among others. Swanzy was later tracked down and killed in Lisburn, County Antrim. This pattern of killings and reprisals escalated in the second half of 1920 and in 1921.
The controversial Economy Act of 1933 is signed into law, slashing $243 million in government salaries and pensions, and veterans' benefits. Despite the economic crisis, super majorities of American economists, policymakers, and the general public believed that the federal government needed to balance the budget and avoid deficit spending, to avoid putting further strain on the bond market which would negatively affect government borrowing costs, banks, corporations, and foreign investors. From 1929 to 1933, the total debt owed by the U.S. government rose from $16.9 billion to over $23 billion.
On 20 March 1943, Mao Zedong became the Chairman of the Communist Party of China, and to enhance the Red Army's military operations, Mao as the Chairman of the Communist Party of China, named his close associate General Zhu De to be its Commander-in-Chief.
On 20 March, Thieu reversed himself and ordered Huế, Vietnam's third-largest city, be held at all costs, and then changed his policy several times. As the North Vietnamese launched their attack, panic set in, and ARVN resistance withered.
On 20 March an aid convoy with medical supplies and doctors reached Maglaj, a city of 100,000 people, which had been under siege since May 1993 and had been surviving off food supplies dropped by US aircraft. A second convoy on 23 March was hijacked and looted.
On March 20, 2008, the IPO underwriters (including JP Morgan, Goldman Sachs & Co., Bank of America Securities LLC, Citi, HSBC, Merrill Lynch & Co., UBS Investment Bank and Wachovia Securities) exercised their overallotment option, purchasing an additional 40.6 million shares, bringing Visa's total IPO share count to 446.6 million, and bringing the total proceeds to US$19.1 billion.
On 20 March, Erdoğan made a speech promising to "rip out the roots" of the Twitter service. Hours later the telecommunications regulator BTK blocked DNS service to the site, citing four court orders the Turkish government had made requiring them to remove content to preserve privacy that had not been heeded. Sources covering the story attributed this to the use of Twitter to share links to the Erdoğan recordings on YouTube. Erdoğan also threatened to ban Facebook.
On March 20, 2014, Facebook announced a new open-source programming language called Hack. Before public release, a large portion of Facebook was already running and "battle tested" using the new language.
In March 2018, Feige revealed that the majority of characters would be back with Marvel Studios, though there were still "some with a couple of other players involved that would have to be negotiated with." The deal was completed on March 20, 2019.
On March 20, 2019, the European Commission imposed a €1.49 billion ($1.69 billion) fine on Google for preventing rivals from being able to “compete and innovate fairly” in the online advertising market.
On 20 March, the government announced that all leisure establishments (pubs, gyms, etc.) were to close as soon as possible, and promised to pay up to 80% of workers' wages, to a limit of £2,500 per month, to prevent unemployment in the crisis.