Minor spoilers for Game of Thrones (S8 E5) below.
In the most recent episode of Game of Thrones, the Golden Company is defending the walled city of King’s Landing and chooses to place their infantry outside the city gates. This also happens in the 2004 movie Troy. I’m wondering if there is any historical precedent for this in the middle ages?
I understand it may have made sense to send your army out to engage an enemy far from the city, or to send troops out for a sortie, but in both of these cases the armies line up at the foot of the walls.
It was done sometimes. If you know that the place is not well-prepared for a siege (e.g., not much food or water), or you think you have a chance to defeat the enemy force before they get expected reinforcements, battle outside the walls can be safer than a siege. Also, if you fight just outside your walls, you can often retreat to safety behind them if the battle goes badly, so the risk of disaster is lower than fighting away from your walls.
This came up recently in https://www.reddit.com/r/AskHistorians/comments/bi2vsc/some_tv_shows_and_movies_would_have_us_believe/ and /u/LuxArdens discussed sorties etc. and I discussed your case, defending by fighting outside your walls.