Gerolamo Emilio Gerini was born in Cisano sul Neva, Province of Savona, Kingdom of Sardinia on March 1, 1860. He was the elder son of Carlo, Professor of Oenology at the University of Turin and Veronica Rosso. After the primary studies he gets a scholarship for talented students and enters the Royal Military Academy of Modena. In August 1879 he graduated second lieutenant of infantry, and was assigned to the 13° Regiment “Pinerolo” in Perugia. In September 1881 he moved to Bangkok, Thailand and joined the Siamese Army where he became a lieutenant.