@Solipsist to be fair, the common sense approach when lacking for information is to not wade in without one...
Backing off, and trying to gather more information before going back in is more often than not the prudent course in life.
It's the same reason why the standard action that modern military often takes when faced with ambush while in a convoy is not to stand your ground...
instead they try to move and break out of the area at best speed through the best route they can see in their current predicament.
The idea is simple, if you are caught in an ambush... your enemy knows the place more than you do most likely.
You have no idea how many of them are there lurking nearby...
Staying put is likely going to be DEATH...
You want to GET OUT... then reassess once you have the chance (possibly with reinforcement)
THEN you get back in if it's prudent and sensible.
So unfortunately even if the young knight didn't have the information, he is still taking the wrong action... he has NO IDEA and that's why he shouldn't PRESS ON while knowing nothing.
Where the story failed however is the part where the younger one has more control over the mercenaries (more ppl) than the older one, despite the clear and obvious difference in their experience and knowledge.
Logically, the older more experienced one should be the one in charge of command of more ppl than the younger rookie...
This is the reason why most military usually require ppl with enough experience before they are given command of larger number of soldiers.