Short answers, pulled from the story.
The war in Donbas was initiated on the 12th of April 2014 by a unit of fifty Russian Armed Forces volunteers commanded by former GRU colonel Igor Girkin, who crossed from Russia into Ukraine and seized the town of Sloviansk. Girkin later stated in the Russian ultranationalist newspaper Zavtra that he pulled the trigger of the war, saying everything would have fizzled out if his unit had not crossed the border.
About 14,000 people were killed in the war in Donbas between 2014 and 2022. The breakdown included approximately 6,500 Russian and Russian proxy forces, around 4,400 Ukrainian forces, and about 3,400 civilians on both sides. Most civilian casualties occurred in the first year of the conflict.
Malaysia Airlines Flight 17 was a civilian passenger jet shot down on the 17th of July 2014 over Hrabove in Donetsk Oblast, killing all 298 people on board. A Dutch-led joint investigation team concluded it was downed by a Buk surface-to-air missile traced to the 53rd Anti-Aircraft Missile Brigade of the Russian Federation, fired from separatist-controlled territory and then returned to Russia.
The first Minsk ceasefire agreement was signed in September 2014. Despite it, Russian-backed forces attacked and eventually captured Donetsk Airport in January 2015. Minsk II was signed on the 12th of February 2015, but separatists launched a fresh offensive on Debaltseve within days and forced Ukrainian forces to withdraw.
Two million people fled as refugees as a result of the Donbas war. The combined population of Donetsk and Luhansk oblasts had been 6.1 million in 2011. Donetsk city alone lost at least 30,000 residents between April and July 2014, according to the city's mayor.
Russia's tanks were documented crossing into Donetsk Oblast on the 11th of June 2014, confirmed by the US State Department, and later photographed in Makiivka and Torez flying the Russian Federation flag. On the 14th of August 2014, a convoy of roughly two dozen armoured personnel carriers bearing official Russian military plates crossed into Ukraine near Izvaryne, which NATO Secretary General Anders Fogh Rasmussen confirmed as a Russian incursion.