The Reaver War of 370 was a major conflict on the spinward border of the Principality of Caledon. Although the roots of the conflict dated back at least a century, including many brutal raids and provocations, the proximate cause of the war was a massive Reaver incursion against a Royal Caledonian Expeditionary Service base in the newly-opened Stirling system.
The war ended with a massive victory for and the annexation of several systems to the Principality, and the beginning of centuries of emnity between Caledon and the Grand Duchy of Marlheim and the Khan World League, both of whom supported the Reavers with covert (and sometimes fairly overt) assistance as the war dragged on. This emnity has led to many incidents between the three powers (and Caledon's ally in the Confederacy of Duncinae).
Prelude To War - 200-349
The Reavers were a constant problem in Reaver's Deep going back well into the Long Night. As the Principality of Caledon began expanding its commercial footprint, Reaver depredations against Caledon's large, active commercial shipping fleet was constant and incredibly costly - causing Caledon to develop a Navy that was large, well-equipped and highly-experienced.
There were innumerable attacks in individual ships and even small merchant convoys in the hundreds of years before 350, and even some larger incursions.
The Sacking of Culloden
In 204, a Reaver fleet sacked the Douglass trading and mining post at Culloden, killing or enslaving thousands, plundering nearly everything of value, and causing the Grand Duchy to abandon all but a small naval outpost in the system, setting the system's development back a century and a half.
The Pillaging of Budwick
In 302, an even larger Reaver force, reacting to expanding private/mercenary activity supporting a Caledonian merchant trading base at Budwick, launched a massive attack on the latter system. Worse, the Reaver fleet fought the responding Caledonian squadron to a standstill before leaving the system. Budwick remained a tense Reaver-infested no-man's land for the next half-century.
The Battle of the Stirling Downport
Stirling began as a small trading post between Caledonian, Aslan and even some more pragmatic Reaver groups. In 350, the RCES established a monitoring base on one of the system's moons, including a small, fortified downport.
Violence between Reaver and Caledonian traders led to a reaction by Reaver forces, who invaded the largely wet world, looting and pillaging the population centers and laying siege to the downport. The RCES scouts and a small civilian militia (including Aslan militants) held off the Reavers even though grossly outnumbered, for a month until help arrived in the form of a Caledonian Navy force under Admiral Ian Saint George Urquehart, Viscount of Halifax.
After a short, sharp battle in which half their fleet was left smoking scrap, the Reavers fled to Glenelg.
Urquehart then launched a two-pronged assault on the main Reaver "base" at Caithness - a feint toward Budwick designed to get the Reavers to either flee or deploy reinforcements, and a thrust to set up a covert refueling base in the Glenelg system. This led to the luring of the bulk of the Reaver fleet to Budwick; Urquehart then attacked on Caithness, destroying much of the remaining Reaver fleet's base and fuel-refining capacity. The Reaver fleet (which included a number of vessels that had been "lent" to the Reavers by the Marlheim and Khan fleets), caught at Budwick with inadquate fuel and supplies, attempted to return to Caithness to re-open its supply lines, and was crushed in the Battle of Caithness on 204-371. The survivors dispersed to Budwick, Culloden and Rejhappur, where they were hunted down and destroyed or captured piecemeal.
Caledonian Army and Marine troops spent much of the next three years patiently reducing and eliminating Reaver strongholds on Glenelg,which fell in 371, Budwick,which was declared Reaver-free in 372, and finally Caithness, which was cleared and absorbed into the Principality in 373.
The presence of massive amounts of Marlheim, Khan and other Reaver clans' money among the Reavers helped set off centuries of emnity between the Principality and its neighbors that is still going strong.