His military ability was tested by an attack from the Sabines. Tarquinius doubled the numbers of equites to help the war effort, and defeat the Sabines. In the peace negotiations that followed, Tarquinius received the town of Collatia and appointed his nephew, Arruns Tarquinius, also known as "Egerius", as commander of the garrison which he stationed in that city. Tarquinius returned to Rome and celebrated a triumph for his victories that, according to the "Fasti Triumphales", occurred on 13 September 585 BC.