Angmar in 1409 concentrated two mighty thrusts against Arnor. The first, and the more obvious (indeed, so obvious as to be suspicious, for Arnor knew long before its coming what its purpose was), was seemingly aimed at the North Downs, Fornost, and the Weather Hills. King Arveleg led the defense of the Weather Hills, whch saw the mightiest army of Angmar, while Prince Araphor and his fiancé Nirnadel were told to remain in Fornost, with Prince Osthir of Cardolan commanding its defense. Once news came of the second thrust south into Cardolan, and how the assault against Fornost was not as strong as believed, Osthir entrusted its defenses to capable lieutenants (which Araphor soon took command over) before planning to march southwards to defend his own domain.

The second thrust was raised (coparatively) covertly in Rhudaur and aimed to march into the wide plains of Cardolan and reak as much havoc as possible once the armies of Arnor were engaged. Once battle was joined on the North Downs and Weather Hills, these smaller, more mobile armies quickly penetrated into Cardolan's heartland, sacking Thalion and then fanning out to lay waste. The two largest detachments went north and south after sacking Thalion - one to Argond, and the other to try to sieze the Barrow-downs and box in the Arnorian armies in the north. Prince Osthir led the Arnorian forces at the Battle of the Downs at Minas Mallost, managing to repulse them at great cost, ultimately dying after being knocked from his horse.
The Battle of the Keep at Argond saw the city damaged but not taken, with the southward march of Angmar averted by a valorous but bloody counter-attack by the men of Saralain under their war-chiefs in conjunction with the garrison of Argond.

The Battle of the Crossing at Sarn Ford was the smallest of the three great battles of Cardolan, but no less important for denying the raiders passage over the Baranduin and access to the inland regions of Arthedain.

Both sides could claim a pyrrhic victory. The razing of Amon Sul, the slaying of King Arveleg, and the sacking of Cardolan were great victories for Angmar that sapped the strength of Arnor. But it had overestimated its own strength, and the valor of the Dunedain. For in the process of these triumphs, it spent such material and manpower that it would dare not try to assail the kingdom in such force again for over four centuries - and when they did once more meet on such scales, it would be Arnor, not Angmar, who took the iniative. The war between Angmar and Arnor entered a period of raids, small scale skirmishes, and cloak and daggers.