The main battery of "Bretagne" used 36-pounder long guns, the heaviest available calibre, instead of the more modern 30-pounder long gun on which other ships standardised their armament. The aft of the ship was round and featured gun ports, like on "Napoléon" on her successors. Although she carried 130 guns of various calibres, "Bretagne" featured no less than 180 gun ports; this allowed the crew to reinforce the artillery on one arc if needed and time permitting, such as before a shore bombardment, and fire up to 80 guns on one target.