The Royal Marines are the three seaborne regiments of the Tierran Army. They are stationed aboard ships of the Royal Tierran Navy and are tasked with protecting Tierran diplomatic envoys. They are armed with bayonets and, unlike most of Tierra's soldiery, rifled muskets.

Following the Battle of Blogia many marines were stripped from their respective ships and used to help replenish the losses among the Tierran infantry sustained during the battle.