Would javelin throwers thrive in a medieval war?

They were used by several armies. The Franks with the Angon (up to the 10th century) The Normans in the Battle of Hastings (against unarmored horses, they were effective). read more

But 3 magonels is overkill, no mangonels but ballistas/trebuchet is much better and still wipes javelin based armies of the map. If anything 3 artillery + Battle support(master tactician, faster orders/artillery) is breaking the game atm. Literely the entire top 10 in EU is using this setup, with ofc some variation in what 6 units/3 artillery. read more

The javelin’s damage is velocity based and, as a result, sprinting and then hurling the javelin causes it to travel farther and deal significantly more damage. Generally speaking, it is an instant kill on all classes (except knight) if a javelin lands in the torso area from a sprinting throw. read more