From Halopedia, the Halo wiki
Unlike its successors, whose pods carry thirty or more missiles, an Ares silo carried only a single missile. Warships historically carried far fewer Ares missiles than Archer missiles. For example, UNSC destroyers in 2494 carried seven Ares missiles total, whereas by 2552, destroyers carried 26 Archer pods of 30 missiles each, for a total of 780 missiles.
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