Arnor- Designed For Failure?

[Zigûr]

Originally Posted by Inziladun

But it has always seemed to me that the Witch-king's victory over them was easier than it should have been.

The division of the kingdom was a significant contributor, as has been stated. The Lord of the Nazgûl "came north with the purpose of destroying the Dúnedain in Arnor, seeing hope in their disunion, while Gondor was strong."
In terms of the "ease" of Angmar's conquest, however, might it also be a factor in the failure of Arnor that it is where Sauron struck hardest first? Gondor endured war and strife through the Third Age as well, of course, and events like the Wainrider wars and the Balchoth invasion were orchestrated by Sauron, but they were largely indirect. It was to the dismantling of Arnor that Sauron brought his strength to bear more directly in the shape of the Lord of the Nazgûl and more traditionally "Sauronic" forces: Orcs, Troll, wolves, evil spirits and the like. The attacks on both realms are calculated, but Angmar's war against Arnor seems more directly "managed" to me, whereas it feels like the invasions of Gondor mostly involved Sauron giving the Easterlings a push in that direction and leaving the rest up to them.

Angmar arose in 1300 but Arthedain didn't fall until 1974. 674 years doesn't seem like too easy a defeat, although of course by comparison to real history the nations of Men in Middle-earth always seem to endure for an implausibly long time. I suppose the longevity of the Dúnedain might account somewhat for that.