Susanowa was a minor Goa'uld in the service of Raiden, who ruled over the planet Hidoma along with its transplanted Japanese population, the Hidoman. He plotted to overthrow his master and went so far as to enable their scientific development and even giving them Goa'uld-adapted technology. In less than half a millennium, he had created a culture which had superior technology to 21st-Century Earth which he was going to use to take his masters place.
Unfortunately for Susanowa this was not to be as, although he only took a handful of Jaffa into his personal confidence, one of his trusted Jaffa betrayed him to Raiden. Raiden immediately ordered Susanowa destroy the entire world and the civilization he had nurtured over time and, with little other choice, Susanowa obeyed.
He dispatched Death Gliders which had been armed with special biological agents, ironically devised by the Hidoman themselves, which soon covered the entire planet in a fast-acting microscopic organism, rapidly killing the human population. This disease wiped out over 93% of the overall population of the planet within 12 days and, as soon as this was confirmed by Raiden, Susanowa was executed for treason. (RPG: "First Steps: The Stargate Unexplored Worlds Roleplaying Sourcebook")