In J. R. R. Tolkien's fictional universe of Middle-earth, the Fords of Isen were fords in the river Isen, guarded by the Rohirrim. As the only crossing of the Isen into Rohan, they were of enormous strategic importance.
During the War of the Ring there were two battles at the Fords of Isen. The first battle took place on February 25, 3019 of the Third Age. The second was on March 2, T.A. 3019. The battles were between Saruman's army and the Rohirrim of Rohan.
Théodred, son of King Théoden of Rohan, was alerted by his scouts to the mustering taking place in Isengard. He manned both sides of the ford and went forward leaving three companies of riders to guard the eastern side. Early in the morning, he crossed over to the western side with a force mainly consisting of archers and cavalry. He planned to take the forces of Isengard by surprise.
However, Saruman had tricked the scouts; his army was already marching out to attack the ford. Twenty miles to the north of the ford, Théodred encountered the vanguard of the Uruk-hai and quickly cut through their lines. He then charged at the main force, who were prepared for the attack and were stationed behind trenches planted with pikes. Reinforcements came out of Isengard and outflanked the cavalry, nearly surrounding them. Hastily Théodred ordered a retreat, but the Uruk-hai could not be shaken off that easily. Grimbold, who was in command of the Rohirrim rearguard, had to cut down their pursuers many times.
Saruman's eastern force was much smaller but more dangerous. It contained mounted Dunlendings, Warg riders, Uruk-hai and half-orcs (or orc-men). The Rohirrim guard on the eastern side of the ford had been driven into retreat, and their attackers recrossed the ford to attack Théodred on both sides. Théodred and his men had dismounted on an islet to cover Grimbold's retreat. At the same time Grimbold's force was being attacked from the western side, and as Grimbold looked east, he saw Théodred's force being driven from the islet to a hill. Grimbold and a few men raced toward Théodred's position. By the time Grimbold reached him, Théodred had fallen, cut down by a great orc-man. Grimbold slew the orc-man and then found himself defending Théodred's body from orc-men. He himself would have been killed had it not been for Elfhelm.