I know they fired their missiles in front of the infantry and then retreated behind once one side charged the other. I know in Agincourt longbowmen joined the melee with their own weapons like hatchets. Was this common? If they didn't do that, did they just wait in the back for the battle to be over? Did they have any other uses besides skirmishing?
Hello
Just to build upon the previous answers and add a more of a crossbowers perspective…
Check Blaise de Monluc’s memoirs. Monluc was a Gascon soldier who (among plethora of other military adventures) described small scale encounters during his command of a mixed “shot” company of crossbowmen and arquebusiers in the early sixteenth century. In one instance Monluc instructs his men to draw swords and use their crossbows in lieu of a buckler. The crossbowers and arquebusiers were also employed in various close combat situations.
In addition, mounted crossbowmen in late medieval Germany and east-central Europe often charged into melee (sword in hand) or had to defend themselves up close. Tallhoffer’s fightbooks show such combat scenarios (such as lancer vs mounted crossbower).
Cheers
Sources:
Monluc, Blaise de. The Commentaries of Messire Blaize de Montluc Mareschal of France. Trans. Charles Cotton. London: Herbert & Daniel, 1913. (see esp. pp 47 – 62)
Cod. icon. 394a - Tallhoffer’s “Württemberg” fechtbuch. Available at Wiktenauer.com