Complex sentence: When General Brun created the French aviation service at Reims in 1909, the logical candidate to command this new unit was Estienne: since the main task of aircraft was seen as directing artillery fire, he seemed the best qualified man to solve the technological difficulties involved.
Split into simpler sentences: When General Brun created the French aviation service at Reims in 1909, the logical candidate to command this new unit was Estienne. Since the main task of aircraft was seen as directing artillery fire, he seemed the best qualified man to solve the technological difficulties involved.