Born in Savigliano on 26 April 1846, Arimondi attended the Royal Military Academy in Modena. After graduating in 1865, he was appointed sub-lieutenant in the Bersaglieri, and fought in the 1866 Italo-Austrian War. Upon reaching the rank of captain he served as a military observer during the Franco-Prussian War. He then attended the School of War and in 1874 was promoted major in the Army Staff.