First Princes' War

The First Princes' War, also referred to as the First Vicarial War, was a series of interlocked civil conflicts in the Kingdom of the Fhainn that lasted from June 1519 to January 1545. It began over a dispute over the rights of vassal lords within the Kingdom and later expanded to a war over succession to the Chathairrih Fhainn by Clyde Barheln through his marriage to the Rih's sister, Bronwyn. It consisted of three distinct phases - the Eastern Campaign, the Protestant Wars, and the Succession War. Depending on the source, it is also described as being either a direct cause of or the parent conflict of the Kurikilan Crusade.

First Princes' War
Part of Vicarial Wars
Location Faneria, Northern Levantia Result Establishment of elective monarchy in Fhainnlannachaeran, establishment of Catholicism as state religion, curtailing of Protestant sects in southern Faneria
Belligerents
Fhainnlannachaeran (Màrtainn and Wydd-Màrtainn Branches)	Fhainnlannachaeran (Barh-Màrtainn Branch, Principality of Daingean)
Units involved
Throneswatch House Guard Army of Maria, Mother of God Crown Army Army of the North (from 1538) Army of Caileansdun Army of Cancale (from 1541) Army of the Rhydheas Army of Cwimbran Army of Dunlann Army of Daingean (from 1541) Army of the Tyn (from 1542) Various Feudal Levies	King's Own Army Army of Christ Reborn Army of the Living God Army of Light Salvation Army Crown Army Army of the West Army of Caslach Army of the Tyn (from 1520-1542) Army of the Rhydwel (from 1520) Army of Daingean (to 1541) Various Feudal Levies
Casualties and losses
significant	significant

Causes

Succession

The succession of the war at its beginning was not in dispute, as the throne clearly passed to the oldest son of Ruaridh III, Caerls. However, after his early death in the war, the throne was claimed by Clyde Barheln, a choice supported by Protestant lords who were willing to overlook Caerls' cousin, Rhys Wydd-Màrtainn, in favor of Clyde, a fellow Protestant.