What was the cause of the mexican-american war?

Sparta faces threats from without and within the city-state who posed these threats.

Which of these is an edge city? boston, ma chicago, il irvine, ca detroit, mi

Plz ! after the first battle of bull run general ivan mc dowell was removed from command of the union army he was replaced by a. general ulysses s. grant. b. general george mcclellan. c. general robert e lee. d. general george meade.