- "Food was scarce, the population was paranoid, and we almost went extinct."
- ―Trevyr Blackgard
The Fourth Border Wars, also known as the Keller Wars was a major conflict in the history of The Borderlands. House Keller, House Blackgard's major rivals, attempted to overthrow the Blackgards and rule the Borderlands themselves. They almost succeeded until Trevyr Blackgard killed Lord Auster Keller and his son, Tylan Keller. LordOfTheNeverThere' short story, The Prowler, details the final days of the war.
Tensions were gradually surmounting between House Blackgard and House Keller. The Kellers, formerly a minor noble house from the Stormlands, successfully managed to elevate themselves to greater nobility with each passing generation. The hostility and rivalry between the two Houses originated when the Kellers began to aggressively expand their mercantile trade and sphere of influence. In order to increase their power, the Kellers desired trade in almost each import/export branch. When they noticed that the Blackgards were getting increasingly wealthier thanks to their successful ebony trade - a rare ore found only in the Borderlands - the Kellers attempted to gain a foothold in that trade as well. First, relations were relatively peaceful as the Kellers maintained diplomatic relations in a way to gain more access to the ebony trade. However, the Kellers grew impatient and their goal to secure the ebony trade quickly turned aggressive. House Keller declared an embargo against the Blackgards, claiming that the latter unfairly monopolized the ebony trade.
When Auster Keller became the Lord of Kell he began preparing for what he thought was an inevitable conflict between the two Houses. The Baratheons, Auster's overlords, were rendered entirely oblivious to Auster's machinations. Auster Keller also possessed a racist streak, and believed the Bordermen to be inferior. He considered the natives of the Borderlands to be unfair hoarders and that they were responsible for robbing the rest of the Seven Kingdoms from the ebony trade.
Trovar Blackgard's council advised him to improve diplomatic relations with the Kellers, as they too felt that a war could happen at any given time. Trovar chose to follow up on his council's advise and went to Kell to parley with his arch-rivals. During that meeting, Auster, for the first time, revealed his racist tendencies, calling Trovar and his people out on their inferiority and stupidity. The proud Lord Trovar refused to hear any more and famously presented Auster with an embroidered jester's hat, suggesting he was the "king of fools". Angered and offended, Auster ordered the Blackgard delegation out of his castle.
The war eventually erupted when Auster Keller had the Maester of Blackgard killed to spite the Blackgards. Lord Trovar Blackgard and his firstborn son, Trevas, considered this an official declaration of war, leaving Blackgard to go to battle.
Initially, the Blackgards were winning the war. However, during an unexpected ambush the Kellers managed to assassinate Trovar. Before Trevas could return to Blackgard to be named the new Lord of Ebonheart he was killed as well, by Tylan Keller himself. Two weeks after Trevas's death the Kellers came riding into Blackgard and had the entire city slums put to the torch. They then killed Aurola and imprisoned Trevyr.
The Kellers had occupied Blackgard for almost nine years. During the time, Tylan Keller attempted to force the former allies of the Blackgards to become allies of House Keller by force. This included trying to force House Tully into an alliance by forcing Lord Ambrose Tully's daughter Addysen to marry him. When the Tullys refused, Auster Keller lead an attack on Riverrrun which inadvertently lead to the death of Addysen. An infuriated Ambrose would later pledge his support to the combined forces of Trevyr Blackgard and Lyonel Baratheon.
The Baratheons, a long-time ally of the Blackgards, were infuriated and demanded for Auster to retreat his forces from Blackgard. The Kellers refused and eventually rebelled against their liege. The war took a more dangerous turn when King Maekar Targaryen branded Auster Keller as a traitor to the crown.
Trevyr, now seventeen, decided that it was time to retake Blackgard and to destroy House Keller. Not by battle, but with sheer brilliance, cunning thinking and scheming. Earning him the nickname: Prowler. He managed to weaken House Keller by politically exploiting them and persuading several houses to stop supporting the Kellers. He also cut the shipment of food, armor and supplies to Blackgard. When House Keller was beginning to lose their grasp on Blackgard, Trevyr and a couple of other companions, killed Tylan in his sleep, leaving the Keller soldiers without anyone to lead them. The Kellers eventually left Blackgard and retreated back to Kell, their stronghold.
After the Kellers were expelled, Trevyr and Lyonel Baratheon marched with their troops towards the castle of Kell and besieged it. The battle of Kell didn't last more than a day and Trevyr was able to make it through Kell's great hall where he confronted Auster Keller in a deadly duel with Trevyr as the victor. While he was struggling to get on his feet, Trevyr's men tied Auster to his bed where they burned him alive. Trevyr ordered his troops to search the hall for Auster's family and eventually found Auster's wife with the last of her three children, hiding beneath the beds. Trevyr's men took the family in custody and brought them to King's Landing for the infamous Execution of the Kellers.
In the aftermath of Fourth Border Wars, the Kellers were no more. Trevyr was ruthless and cunning, and soon he defeated the Kellers and burned Kell to the ground. Trevyr put all surviving Keller to the sword, man, woman and child, to make an example of them for anyone who would dare challenge House Blackgard's dominance again. Trevyr subsequently had the corpses of the executed Kellers hung from the gates of Blackgard on public display. Trevyr later explained that he rather wanted the war to end peacefully. However, in order to make sure that the Blackgards would never face such a crisis again he had to inflict fear into people.
The extinction of House Keller marked the first major step in the return to glory of House Blackgard, in which Trevyr almost singlehandedly rebuilt the fortunes and strength of his House.
Trevyr's victory was immortalized by the minstrels in the popular song, Rainbow Rising.