skirmish

an episode of irregular or unpremeditated fighting, especially between small or outlying parts of armies or fleets.

Merriam-Webster Online Dictionary
skirmish (noun)
1.
a minor fight in war usually incidental to larger movements
2.
a) a brisk preliminary verbal conflict
b) a minor dispute or contest between opposing parties - the debate touched off a skirmish
skirmish (verb)
intransitive verb
1.
to engage in a skirmish
2.
to search about (as for supplies) scout around