Paul I of Russia
Paul remained overshadowed by his mother for most of his life. His reign lasted four years, ending with his assassination by conspirators. He adopted the laws of succession to the Russian throne—rules that lasted until the end of the Romanov dynasty and of the Russian Empire. He also intervened in the French Revolutionary Wars and, toward the end of his reign, added Kartli and Kakheti in Eastern Georgia into the empire which was confirmed by his son and successor Alexander I.
Saint Michael's Castle
Paul I was assassinated only 40 nights after he moved into his newly built castle. He was murdered on 12 March 1801, in his own bedroom, by a group of dismissed officers headed by General Bennigsen. The conspirators forced him to a table, and tried to compel him to sign his abdication. Paul offered some resistance, and one of the assassins struck him with a sword, and he was then strangled and trampled to death. He was succeeded by his son, Emperor Alexander I, who was actually in the palace at the time and was informed of his accession by General Nicholas Zubov, one of the assassins.