Relations between the Kingdoms of Gondor and Arnor

The Realms-In-Exile were founded by the Faithful Numenoreans who survived the fall of Numenor in 3320 Second Age (SA). After the War of the Last Alliance (3434-41 SA) the relative standing of each throne changed, with Gondor growing to become a mighty power, whereas Arnor split into three seperate kingdoms, Cardolan, Rhudaur and Arthedain and declined in strength until it was destroyed in war with Angmar.
In the Second Age Gondor was ruled cojointly by Elendil's sons Isildur and Anarion. Elendil ruled in the northern realm of Arnor and was High-King of Gondor and Arnor. The institution of…