Halo's Marathon class as a fleet backbone and deterrent

In Halo, Marathon-class heavy cruisers are reliable ships at the backbone of the UNSC fleet. The case for building more of them is that ships at this level supply useful mass below larger warships. A heavy cruiser can justify itself without fighting if its arrival changes an opponent's calculation. The examples come from several Halo books and possibly one game, though the game is not identified. Human factions abandon hostile plans when one appears. The fictional examples carry a real force-structure lesson: fleets gain leverage from numerous credible ships whose presence can prevent a fight.