A masked ball took place at the Royal Opera House in Stockholm at midnight on 16 March 1792. King Gustav III had arrived earlier that evening to enjoy a dinner in the company of friends. During dinner, he received an anonymous letter that contained a threat to his life, but, as the 
king had received numerous threatening letters in the past, he chose to ignore it, and, after dining, left his rooms to take part in the masquerade.Soon upon entering, he was surrounded by the conspirators.. The king was easily spotted, mainly due to the breast star of the Royal Order of the Seraphim which glowed in silver upon his cape.
The conspirators were all wearing black masks and accosted him in French:"Bonjour, beau masque!"
They moved in behind the King and fired a pistol-shot into the left side of his back. The King jumped aside, crying in French too:
"Ah! Je suis blessé, tirez-moi d'ici et arrêtez-le"
The King was immediately carried back to his quarters, and the exits of the Opera were sealed. Conspirators were arrested the following morning, and immediately confessed to the murder.
The king had not been shot dead, but was alive, and continued to function as head of state. The coup was a failure in the short run. However, the wound became infected and on 29 March he finally died, his last words being:
The king had not been shot dead, but was alive, and continued to function as head of state. The coup was a failure in the short run. However, the wound became infected and on 29 March he finally died, his last words being:
"Jag känner mig sömnig, några ögonblicks vila skulle göra mig gott" ("I feel sleepy, a few moments rest would do me good")
in Wikipedia
