Use the adverb gallantly to describe something done in a heroic or chivalrous manner. You can gallantly slay a dragon or gallantly offer an elderly man your seat on the bus.
Think of the lyrics to the "Star Spangled Banner," which describe the “broad stripes and bright stars” that were so “gallantly streaming.” The flag was waving gallantly — meaning bravely and grandly — through the battle. But you don't have to be in a war to do something gallantly. You might play gallantly during the second half of the championship game to lead your team to victory.