Short answers, pulled from the story.
Domitian was Roman emperor from 81 to 96. His 15-year reign was the longest since Tiberius, beginning on the 14th of September 81 following the death of his brother Titus and ending with his assassination on the 18th of September 96.
Domitian was stabbed seven times on the 18th of September 96 by court officials acting in a coordinated conspiracy. A steward named Stephanus carried out the act, having feigned an arm injury for several days to conceal a dagger. The main organizer was Domitian's chamberlain Parthenius. Domitian was 44 years old at his death.
Domitian erected, restored, or completed around fifty structures in Rome, second only to Augustus in scale. His most significant projects included the Flavian Palace on the Palatine Hill, the Stadium of Domitian (now the site of the Piazza Navona), the Odeon of Domitian, the restored Temple of Jupiter Optimus Maximus with its gilded roof, the Arch of Titus, and the completed Colosseum interior.
Damnatio memoriae was a formal condemnation of memory passed by the Roman Senate on the day of Domitian's assassination in 96. His coins and statues were melted down, his arches torn down, and his name erased from public records. On existing portrait reliefs such as the Cancelleria Reliefs, his features were recarved to resemble his successor Nerva.
The Dacian wars began around 84 or 85 when King Decebalus crossed the Danube into Moesia and killed the Roman governor Oppius Sabinus. After initial Roman setbacks, including the death of the praetorian prefect Cornelius Fuscus and the loss of the Praetorian Guard's battle standard, the Romans defeated Decebalus in late 88 under general Tettius Julianus. Domitian negotiated peace, granting Decebalus an annual subsidy of 8 million sesterces.
The main ancient sources on Domitian, including Tacitus, Pliny the Younger, and Suetonius, all wrote after his death when the Senate had condemned his memory to oblivion. Tacitus had a personal motive: his father-in-law Agricola may have been recalled from Britain by Domitian. Modern historians, beginning with Stephane Gsell's 1894 reassessment and Brian Jones's 1992 The Emperor Domitian, argue the hostile portrait reflects senatorial bias rather than Domitian's actual record.