Crusades, of course, are holy wars, though the term has taken on a less….charged meaning these days. (“She’s on a crusade to get everyone to play Dragon Age.”)
The wiki points out:
The Exalted Marches are religious crusades led by the Chantry, though the first Exalted March was that of Andraste against the Tevinter Imperium, and thus predates the Chantry proper. The second Exalted March was against the elves of the Dales, who had been Andraste’s allies during her fight against the Imperium but whose relations with Orlais and the Chantry had deteriorated to the point of war by the time of the early Glory Age. During the Black and Exalted Ages, four Exalted Marches were called against the “heretical” Imperial Chantry. More recent are the three Marches against the Qunari invaders during the Steel and Storm Ages.
The Christian church has a checkered history when it comes to crusades — marches are an apt comparison.
The first crusade was called in 1095. The Byzantine Empire was under attack by the Muslims. The emperor sent a plea to the pope several times, asking for help. Finally, Pope Urban II agreed to call for a crusade in 1095.
You’ll notice this is just 40 years after the East-West Schism. The pope called the crusade in part because he was hoping to reunite the two churches. Crusaders were promised remission from sin (basically, they were blessed); many joined the crusade hoping to gain land and/or wealth, as well.
Unfortunately, as the Crusaders marched across Europe, they often attacked Jews and other minorities. Later Crusades would see the Europeans attacking other Christians.
The Fourth Crusade, for example, saw the Crusaders attacking the Christian city and Byzantine capital Constantinople in 1204.
In 1209, the Albigensian Crusade was launched. This Crusade sought to destroy a sect of Heretical Christians in France, the Cathars.
As we can see, Crusades and Marches weren’t just about a hated enemy, but also about getting rid of politic enemies, rival factions, and former allies.