Rennella was born in Italy on 15 February 1890. In 1892 he accompanied his family when they emigrated to
Guayaquil,
Ecuador. While there, his name was changed to fit the pattern used in many Spanish-speaking countries to be Cosimo Rennella Barbatto by appending his mother's maiden name, though he was usually called "Cosme". In 1909, he volunteered to serve in the Patria I Battalion in military operations against
Peru. In 1911, Rennella persuaded a local sportsman's club, the
Club Guayas de Tiro y Aviacion (Guayas Shooting and Aviation Club), to sponsor his pilot's training; his aim was to be the first flier in Ecuador. The club underwrote Rennella's journey to
Pau, France to learn to fly. There Rennella became a pilot using French
Blériot military aircraft. He finally qualified for his civil pilot's license at
Turin's
Chiribiri flying school on 24 August 1912. Following that, he accompanied a pair of
Nieuportish
monoplanes back across the Atlantic to
Panama. By the time Rennella and his two traveling companions returned to Central America with an aircraft, the first flight in Ecuador, which was by Chilean
Eduardo Molina Lavín, had taken place in their absence. Rennella's new aircraft was a copy of a French
Nieuport, built by Navaro and Valgoi of
Turin, Italy. On 15 December 1912, having been forbidden to fly across the
Isthmus of Panama by U. S. officials, he flew an unauthorized flight in this aircraft over
Panama City, leafletting the town with fliers thanking the populace for their support of his flight, in what may have been the first aerial pamphlet drop in history. In January 1913, he was welcomed home to Ecuador. Once there, he accepted the obligation of returning to Italy for more training while he supervised the manufacture of a
Chiribiri monoplane for his Club sponsors. He brought this aircraft, dubbed
Patria No. I, back to Ecuador. He used his time in Italy to qualify for an Italian military pilot's license, which was granted at Turin on 25 July 1913. Rennella was back in Ecuador by 29 September 1913. On 8 October 1913, at
Guayaquil, Cosimo Rennella became the first Ecuadorian citizen to fly in his own country. A follow-up exhibition scheduled for the 19th was cancelled amid controversy over potential gate receipts. Rennella may have briefly served in the Ecuadorian military before
barnstorming in Peru,
Chile, and Mexico. He founded a flying school in Mexico. Italy's 24 May 1915 entry into World War I caused his July return to Italy, where he begged the War Ministry to allow him to volunteer to fly for them. ==World War I==