Collocations for defend - verb

adequately, effectively, properly (esp. BrE), successfully
Computer users need to ensure their systems are properly defended.
She successfully defended herself against an attack from someone larger and stronger.

heavily
The city was heavily defended against attack.

lightly
They attacked the left flank, which was only lightly defended.

against

actively, aggressively (esp. AmE), fiercely, passionately, robustly (BrE), strongly, vehemently, vigorously
The company has vigorously defended its decision to reduce the workforce.

staunchly, steadfastly, stoutly (BrE), valiantly
adequately, effectively, successfully
publicly

against
She defended her department against accusations of incompetence.

successfully

against
The champion successfully defended his title against the challenger.

Defend is used with these nouns as the subject:
soldier

Defend is used with these nouns as the object:
airspace, base, castle, championship, choice, country, crown, decision, democracy, dissertation, doctrine, flank, freedom, frontier, homeland, honour, integrity, interest, liberty, majority, nation, nest, pass, perimeter, position, practice, prerogative, realm, religion, republic, reputation, right, seat, shore, slavery, sovereignty, status quo, suit, system, territory, thesis, title, tradition, trophy, turf, view