Battle of Fornost

The main army was from Gondor. But elves from Lindon and Northmen were there too. So too was a company of hobbits that never made it back to the Shire.

The battle took place on the plains outside the old capital of Arthedain.

In line with the Cult of the Offensive, the Witch King marched out of his fortress to meet the attackers in open battle. However, Gondor exploited their speed to their advantage. They were able to get to the area first, which allowed their cavalry to hide in the Hills of Evendim. The battle did not go too well for Angmar. After a lot of hard fighting, Angmar's forces were forced to retreat. At this point the hidden cavalry force attacked from behind. Which led to the total destruction of Angmar's army. The Witch King tried to retreat and rally his forces, but they were too broken and trapped by ab elvish army sent to block their escape. Too many of his forces were sent to the battle, so there was nothing left to defend his main fortress.

This led to the complete destruction of Angmar's forces and the eviction of the Witch King from the area. Apparently not a single orc or man loyal to the Wich King was left alive west of the Misty Mountains.

The Dúnedain were never able to recover. The region remained sparsely populated. Only the Rangers of the North provided something resembling a government. So in one sense, Mordor was able to achieve a great victory by destroying a major concentration of enemy power.   But just as importantly, Angmar itself fell. Should the Witch King have won, the area would have stayed under his control. Which means that Sauron would have had a significantly increased territory under his control. Which then means more troops, economic resources, flexibility, strategic depth and so forth. The War of the Ring would have been practically impossible to win should Angmar have survived.   Then, there is the whole issue of the One Ring. Moria and Rivendel would have likely fallen. The War of Dwarves and Orcs would have gone much worse - probably ending in a defeat for the Dwarves. Which on one hand makes it much more likely that Sauron would have found the One Ring. Plus, there would have been much less friendly territory for the ring bearers to hide. Basically, this battle allowed the Free People to remain free. Even if it took many years to see and a huge cost.