Dismount is a command that exists in Fire Emblem: Mystery of the Emblem, Fire Emblem: Thracia 776 and TearRing Saga: Utna Heroes Saga. Units riding on horse, pegasus, or wyvern are able to dismount to an on-foot version of their class. Often, dismounted units may also be forced to use swords only. Their movement is reduced, but this is often a necessary sacrifice as it reduces their movement being impeded by forests or similar terrain and also negates the Weapon effectiveness of horse-slaying or flying-slaying weapons.
In indoor chapters, characters automatically dismount, while they will need to dismount to enter indoor regions in outdoor chapters. Seliph is also able to dismount in Fire Emblem: Genealogy of the Holy War, although it offers no real benefits and may be cause of many glitches. Meanwhile, mounted units in Fire Emblem: Radiant Dawn have reduced movement indoors. Unused game data in Fire Emblem: Shadow Dragon suggests that dismounting was planned to be implemented at one stage.
Dismounting in Fire Emblem: Thracia 776 heavily decreased the effectiveness of lance and axe using classes who were not able to use lances and axes on foot and could not use swords mounted. In most cases the character had their sword skill at Rank E like Glade, meaning they had to train heavily to avoid being helpless indoors. This also left the player with no indoor lance users other than latecomer Xavier and a promoted Dalsin, both of whom had their lance skills at Rank E. Arch Knights Selfina and Robert, however, still use their bows while dismounted as they are unable to ever equip swords. One advantage of dismounting is that the units will gain more experience when fighting on foot than they would on horseback.
This wasn't much of an issue in Fire Emblem: Mystery of the Emblem and TearRing Saga: Utna Heroes Saga. Both games feature the common Weapon Level stat and powerful indoor lance users like Dolph, Draug, Lionel, and Sheema. The Commando Knight and male Dragon Knight classes in TearRing Saga also retained their usage of lances indoors.