The West Marches of Rohan¹

Running northward from the White Mountains, the western border of Rohan was marked by the course of the river Isen, and among the Rohirrim this border region of their realm was known as the West Marches. Its most strategic point was at the Fords of Isen, where the river broke briefly into two shallow branches, and over which the North-South Road ran through the Gap of Rohan.

The Rohirrim constructed forts to guard the Fords, forts that were tested in the year III 3019 when Saruman sent his forces against Rohan. Because Saruman controlled the sources of the Isen, he was able to send his soldiers down both of its banks, and a part of his force raided southwards through the West Marches themselves. The ensuing Battles of the Fords of Isen sorely tested Rohan's defences, seeing the King's heir Théodred slain in the First Battle, and the Fords themselves captured in the Second Battle. Rohan's loss of the Fords and the West Marches set events into motion that would lead to the Battle of the Hornburg the following day.

A little confusingly, the western borders of Rohan contain two distinct regions with almost identical names. The West Marches were the northern part of Rohan's western border, following the course of the Isen. The West-march, despite the closely similar name, lay lower on the course of the Isen, forming a tongue of land between that river and the Adorn to the south.