Complex sentence: Relations between Continental Army officers from the East (such as Brodhead) and western militiamen were frequently strained, and made worse by the U.S. government policy of attempting to recruit certain American tribes as allies.
Split into simpler sentences: Relations between Continental Army officers from the East (such as Brodhead) and western militiamen were frequently strained. The tensions were made worse by the U.S. government policy of attempting to recruit certain American tribes as allies.