As far as one can see, warfare is always defined by the leading army that at some point dominated a region. For instance in Europe in the XVII century one of the most famous and effective "army" was the Spanish Tercio. Watching the movie of Alatriste in the final scene, I have always wondered if the battle beneath the pikes was common during the period. This is somehow at odds because Hollywood movies always depict most of the time e.g. Romans, medieval battles without this technique. So my questions are:
Was this common during an encounter between the armies?
Does it have a particular "name"?
Was there an appointed unit to specifically do this? (In the movie the "musketeers" are the guys going below.)