During what is dubbed the battle of the bastards in season 6 episode 9, John Snow is in battle with the Boltons. Outnumbered 2:1 the fight goes about as expected, John Snow's army is surrounded by pike men and are almost defeated until Sansa and the knights of Vale ride in and save the day.
My questions are: Firstly, was the surrounding of Snows army with pole arms and a wall of shields a valid strategy used during the medieval period. (Examples If possible)
And if so; what could be done to overcome such a strategy, or prevent them from being surrounded in the first place, without the help from additional cavalry.
Tl;dr: Could Snow have won the battle without the help from the knights of vale.
I'm on mobile so apologies if this comes out as one big chunk of text.
I wrote a long analysis of the battle here. I still need to get around to rewriting the section on cavalry warfare and it's very informal in tone, but you may want to check I out.
As for whether or not Jon could have won without the Knights of the Vale, I don't think so. He would have needed much higher quality troops and probably a good many more archers.
Not to discourage further answers, but u/Valkine, u/Iphikrates, and others, already discussed the Battle of the Bastards here.
Hope this helps!