ADJ. left, right | north, northern, etc. | lower the lower flanks of Vesuvius | mountain
VERB + FLANK attack They decided to attack their enemy's southern flank. | defend, protect | expose West Ham exposed the right flank of Norwich's defence (= showed that it could be attacked easily).
FLANK + NOUN attack
PREP. along a/the ~ along the eastern flank of Greenland | down the ~ a beautiful pass down the right flank | on a/the ~ The army was attacked on the left flank.