The First Intercontinental War [other terms] was a conflict fought between the Jirenes Empire and the nation of Agata at the historical height of its dominion over Ijeida. Though the war was the culmination of ongoing tension between the two powers over exploration and trade, its proximate cause is often cited as the Jirenes seizure of small islands in the Encircled Sea and the unauthorized establishment by Teugad Naufair of petroleum pumps in the southern tip of Griana. It was fought heavily at sea, where the then-dominant Agata Navy had a strong advantage, and by unprecedented infantry armies on the shores of Griana.

Jirenes ultimately overcame Ijeida resistance and established a large occupation force, largely comprised of TeuNau officials, to govern Griana and the Rivering. Agata remained nominally free of Jirenes administration after the war, but Koriarch Farand do Atalei was forced to submit Agata to suzerainty under the Jirenes-dominated Trade Parliament and lost her nation's historic influence over the continent.

This war and its aftermath paved the way for the Ijeida Revolution and the Second Intercontinental War, a generation later.