Flank adjectives are listed in this post. Each word below can often be found in front of the noun flank in the same sentence. This reference page can help answer the question what are some adjectives commonly used for describing FLANK.
american, british, confederate, east, eastern
exposed, extreme, french, german, great
left, light, long, new, north
northern, open, opposite, other, outer
own, rear, right, south, southern
unprotected, west, western, white
Hope this word list had the adjective used with flank you were looking for. Additional describing words / adjectives that describe / adjectives of various nouns can be found in the other pages on this website.