The Northwind Agreement was a pact made between the Federated Suns First prince Hanse Davion and the mercenary group Northwind Highlanders. Called The Homecoming by the Highlanders, the agreement took effect in late 3028 and lasted until their independence in 3057.
With the Highlanders creation in 2362, and the near immediate colonization of Northwind, the group would come to be one of the most respected military forces even before the Star League was formed. The League's fracture in the wake of the Amaris Civil War eventually led to House Liao's acquisition of Northwind as the Great Houses all sought to secure their borders and consolidate power. Naturally, the Highlanders would sign an exclusive defense contract with the Capellan government.
Northwind soon became a target of the Federated Suns during the Second Succession War. In 2841, House Davion sent an invasion force that overwhelmed the defending Stuart's Highlanders and Third Kearny Highlanders. Unable to match the attackers or hold out long enough for reinforcements, the two Highlander regiments fought to the last in defense of their world.
The loss of their homeworld was a devastating blow to Highlander morale, though the company would remain loyal to each other and their Capellan masters with the promise of retaking Northwind when the conditions were right. However, as the decades passed, it became apparent that such a promise could never be fulfilled. Nearly two centuries would pass before a renewed hope of return would present itself. In 3028, at the beginning of the Fourth Succession War, Hanse Davion's champion, Ardan Sortek, made an offer of alliance to the four remaining Highlander regiments. They would leave the service of the Capellan Confederation in exchange for garrisoning Northwind and certain other concessions. The offer was too tempting, and the vast majority of the warrior cabal voted to accept the offer. Some of the Highlanders chose to stay behind, including Clan Jaffray, but the rest of Highlanders abandoned their positions along the Capellan-Suns border and returned to their ancestral homeworld as speedily as they could.
The returning Highlanders arrived on 12 January, 3029, and immediately began engaging a DCMS taskforce attempting to take the planet. The Highlanders fought fiercely in defense of their reclaimed world, forcing the Combine to retreat and saving the survivors of the AFFS garrison stationed there. Since then, the presence of four experienced Highlander regiments, all keen on proving their value to their new liege, effectively blocked the Combine campaign into the Terran region.
The desertion of the Highlanders sealed the fate of the already besieged Confederation, leading to the easy loss of dozens of worlds. The Northwind Highlanders would soon become a important part of the Federated Suns military, but the agreement itself was far from perfect. They weren't independent and relations with the Federated Suns remained strained. In 3057, the Capellan Chancellor Sun-Tzu Liao managed to weaponize the state of the Highlander/FedSun relationship by sending Loren Jaffray, a descendant of a Highlander who stay loyal to House Liao, to convince the Highlanders to fight for independence from the Suns during Operation GUERRERO.
The Highlanders ultimately chose to fight for their independence and successfully forced the Lyran 3rd Royal Guards off world. Supposedly, Jaffray's mission was to destroy the Highlanders for their betrayal, but Sun-Tzu seemed content to simply deprive the Federated Commonwealth of their military might and just accepted Jaffray's defection to the Highlanders. Still, the Confederation never forgot or forgave their treason. During the Dark Age, Chancellor Daoshen Liao launched a massive invasion against Northwind (Operation CLARITY) to finally punish the Highlanders and erase their stain on Capellan history. The Battle of Northwind lasted from 13 November to 15 December, and despite having Canopian and Draconis support, the campaign ended in a defeat for the Liao taskforce. 
- Northwind Highlanders, p. 8, "The Darkest Hour"
- Handbook: House Davion, p. 60
- NAIS The Fourth Succession War Military Atlas Volume 1, p. 40, "Overview"
- Handbook: House Davion, p. 79, "Timeline: Fourth Succession War through the Clan Invasion"
- Northwind Highlanders, p. 9, "Homecoming" & p. 24, "Situation"
- Highlander Gambit p.350
- Shattered Fortress, p. 97