In early 1927, Rowell as commander of the squadron VO-1M, deployed to Nicaragua as part of the United States occupation during this time referred to as the Banana Wars. They arrived at the port of Corinto on February 25 and proceeded to Managua where they began training and flying in support of their fellow Marines on the ground. On July 16, 1927, a 37-man Marine garrison in Ocotal was surrounded by several hundred sandinistas led by Augusto César Sandino. Upon getting news of the attack, then Major Rowell, flew a 5 plane detachment of DHs to help relieve the garrison. The dive-bombing runs from low altitude made by Rowell and his men marked one of the first coordinated dive-bombing attacks in aviation history. Rowell was awarded the Distinguished Flying Cross and the Navy Distinguished Service Medal for his extraordinary heroism and exceptionally meritorious service in action against hostile Nicaraguan bandits during this time.