Last session I DMed, I killed a player's character.
The party wanted to assassinate the main political figure in a town. To inspire general dislike, I made the political figure a racist thug. I run a game with an anything-is-possible mindset. The group believed the assassination would be easy. The party assassinated the political figure during a meeting, yet the party was shocked when, immediately after the assassination, into the room poured a horde of city guardsmen, too many for the PCs even to consider fighting.
Most of the PCs successfully retreated, but one player's character found himself at the end of the initiative order and died in a hail of crossbows bolts.*
The player said I hadn't given his character a chance to escape. I said that I only did what any city guard would have done given the situation.
Should I have allowed the player's character an opportunity to escape despite the character's place in the initiative order not allowing an escape?
* To give the death context: The Town was large with a heavy military presence. It was a very sloppy plan of action. Next to no preparation was put into it. The character that was to be assassinated was heavily guarded. There were three entry ways into the hall, all of which were entered by 8 guards each. I rolled fairly low on the initiative for the three sets of guards but none as low as the character that was killed. The party all made their escape through the various windows, at which point the character was the last option as a target. It should also be noted that he was flying due to being an Aarakocra, which made the crossbows the only form of viable attack. The result was the three sets of guards getting their attack in before he could have escaped.