reconcile, propitiate, placate, conciliate, meet halfway, hold out the olive branch, heal the breach, make peace, restore harmony, bring to terms. settle matters, arrange matters, accommodate matters, accommodate differences
set straight
make up a quarrel
come to an understanding, come to terms
bridge over, hush up
make it, make matters up
shake hands
mend one's fences [U.S.]. raise a siege, lift a siege
put up the sword, sheathe the sword
bury the hatchet, lay down one's arms, turn swords into plowshares
smoke the calumet of peace, close the temple of Janus