For the entirety of the Republic's short history, it was dominated by an elite political class that was not native to the Republic itself. Based on the island of Jovinium, the Republic was not led by natives of the island. Instead it was led by the descendants of rebel heroes, their families and traditions those of neighbouring Varantium.
Harmon Dermeticus was the first native of Jovinium to assume the post of Consul of the Republic. While most regular citizens of the Republic care only for peace and prosperity, the elite patriot ruling class had been jingoistic from the start, desiring to exterminate all spirits and see the Dominion destroyed. Harmon Dermeticus, however, represented those who wanted peace.
After the death of the Arbiter of the Dominion, the Dominion was thrown into chaos. It could no longer pursue any ambitions of conquering the Republic in the nea future. And so, Harmon Dermeticus entered into talks with the Curia of Varantium to declare an end to the hostilities between Republic and Dominion, and bring in a new golden age of peace and trade. This threatened the power base of the patriot class, and Harmon Dermeticus was assassinated by those who would then become the Triumvirate. This allowed the warmongerers to resume power, and declare an invasion of Varantium to coincide with the Eclipse.