Brock Tarly was a battleship captain who fought in the Corporate Wars for one of the independent nations involved in the conflict. During one of the battles, he ordered a tactical nuclear strike on a strategically important mine. Because of poor working conditions at the site, the attack was far more deadly than he had assumed, and resulted in over a million casualties. Brock had in fact been following ROW and acted on incomplete intelligence.
Brock's ship was assigned to attack the Lanowar 8 mining outpost. He was armed with the then-latest weapons technology from his government, a multi-warhead bunker-busting nuclear device. He had understood the weapons were low yield(between 40 and 50 kilotons each) and that they would 'penetrate deep into the ground and destroy the mining infrastructure'. He(and his superiors) had also assumed that the mine itself would be spaces relatively far from the civilian population center.
The attack was further in response to hostile actions made by Mee-Apostrophe-M Corp., and was thus considered a reasonable proportional response. All of this was discussed at the war crimes tribunal(held by the the Gudersnipe Foundation, the Alliance, and the Runarins), and agreed that, based on these assumptions alone, the attack was justified.
However, two major factors influenced the final outcome. First, the weapon(which had never been tested), proved far less accurate than it's designers intended, with a spread much wider than specified and at least three warheads air-bursting. Second, Mee-Apostrophe-M was in violation of approximately every safety law in existence as well as basic common sense.
Brock's ship dropped out of FTL, fired the weapon, then jumped back; relying on automated target acquisition systems to do the rest. The weapon was programmed to lock on the various features that would help find the mine, which was assumed to be located a safe distance from the city center.
However, the mine was actually located directly beneath the settlement; which itself was little more than a ramshackle collection of hastily-built shanties. There was no plumbing or utilities, and the city sewage flowed into the mines.
The weapon's targeting was not accurate, and several munitions exploded prematurely, resulting in a direct nuclear attack on a city of roughly two million inhabitants. These were mostly indentured laborers, little more than slaves, and very poorly educated. With health and safety being beneath the concerns of the mine owners, there was no emergency response available.
This was the cause of the exorbitant death tole. It is surmised that the attack itself only directly killed about 200,000. At least 100,000 more died in either the rubble or the fires touched off by the bombs. The rest of the casualties were the result of no available medical supplies or emergency training. About 400,000 of these were people injured or irradiated in the blast. The rest were healthy survivors, who died thanks to a lack of resources; either of disease or starvation.
Brock was charged at the war crimes tribunal with Crimes against Humanity and waging a War without Quarter. He was later acquitted of the second charge, but the first stood. In light of mitigating circumstances, the three participants in the tribunal recommended leniency; Brock was even on the list of officers to receive full pardons for a time.
However, his own government, in an effort to save face over the incident, declared it's open intention to execute him upon his return home. Brock requested and was granted political asylum by the Gudersnipe Foundation, under the agreement that he plead guilty to his crimes. Under Foundation law, this should also have carried the death penalty, however he was able to avoid this by voluntarily going to a penal colony to serve out his sentence.
According to the official record, Brock was sentenced to the Rukkollo Supermax; however it is well established that as he was neither violent nor dangerous, he was mostly likely a made trusty and lived outside the actual prison. It has been speculated that given his background, he likely was given a job as a guard captain. After his death the Foundation would later confirm that he had indeed received preferential treatment; and while he died at the colony he led 'a rich and colorful life'.