A Watershed Moment in Close Air Support: The 1927 Battle of Ocotal

Major Ross Rowell, USMC

Less than a year had elapsed in Nicaragua since the last civil war and American intervention (1912-1925) ended when liberal and conservative factions in the unity government broke into open rebellion on 2 May 1926 with conservative factions representing the Managua government. On 24 January 1927, the 400 Marines arrived in-country at the request of the government as events proved beyond Managua's ability to control. Accompanying the initial group of Marines was the Marine Observation Squadron VO-1M, led by Major Ross Rowell. In the years following World War I, Marine aviation was very much a lean force, so much so that Marine aviators like Rowell had to be temporarily assigned to the Army to get flight training. Rowell's tour of duty with the US Army began in 1923 at Kelly Field in San Antonio, Texas. There he was assigned to the 3rd Attack Group, an Army squadron that had been established in 1921 to specialize in ground attack. The unit had experimented with a variety of aircraft during this period which were to have been designed for the role of ground attack (and distinct from long-range bombing) on the battlefield, but most designs were wholly inadequate for the roles envisioned by the Army unit. The unit ended up experimenting with the De Havilland DH-4B for ground attack as the aircraft was plentiful, available, and had been used by the British in the ground attack role in the First World War. Using the DH-4B, the unit experimented with dive bombing, which to be more accurate was more glide bombing- the distinction being that glide bombing involved descents of about 45 degrees while dive bombing was quite a bit steeper, approaching 70 degree or more. British experience in the First World War had shown that steep attacks greater than 45 degrees were needed to attack ground positions and while ground attack in the First World War never proved decisive, the seeds of the idea had been planted and were being sown further by the unit that Major Ross Rowell was assigned to. Their DH-4Bs were modified with underwing racks that could hold 10 small bombs. The aircraft was less than suitable for the role and the unit's work had concluded that attacking aircraft would be exposed to hostile fire during its attack that the mission would be of little use. 

Despite the inadequacy of the DH-4 biplane, Rowell held the opposite view as a result of his time with the Army in San Antonio. Given the number of interventions the Marines were conducting in the 1920s, Rowell was convinced that an aircraft making a steep glide or dive attack would be useful for close air support in the small guerrilla wars that the Marine Corps were being committed to throughout Latin America during the interwar period. Upon his return to the Marines from his tour with the Army, Rowell was given command of Marine Observation Squadron One (VO-1M) based at North Island in San Diego. VO-1M had just returned from the Marine intervention in Santo Domingo and based on their experience there, was designated the aviation asset to accompany Marine expeditionary forces being sent overseas. As such, Rowell instructed the pilots of VO-1M in glide and dive bombing based on his experiences with the Army's 3rd Attack Group in Texas. He relentlessly trained his men against simulated ground targets as well as seaborne targets. In February 1927, VO-1M was given orders to deploy to Nicaragua to support the Marines there that landed the previous month. By the end of February, Rowell had the unit's DH-4B biplanes flying a variety of missions ranging from observation and reconnaissance, shuttling messages amongst the various Marine garrisons in the country, and supporting assaults against the rebels who called themselves Sandinistas after their leader, Augusto Cesar Sandino. Prior to the arrival of VO-1M, most air missions during the civil war were flown by the Nicaraguan Air Service which didn't amount to much- two converted civilian Laird Swallow biplanes flown by mercenary pilots that dropped dynamite on the Sandinistas. Needless to say, it wasn't terribly effective and for the most part, the Sandinistas ignored the aircraft until VO-1M arrived. 

Marine DH-4B. Note the Ace of Spades logo of VO-1M. 

On 17 July 1927, a large Sandinista force of 800 men attacked the small Marine outpost at Ocotal near the Honduran border about 125 miles from the capital, Managua. Defending the outpost were 37 Marines and less than 50 Nicaraguan National Guard. The attack opened at 3:00am and it wasn't until 10:15am in the morning that the Marine HQ in Managua became aware of the attack after a Marine patrol overflew Ocotal and saw the gunfire. Major Rowell mustered five DH-4Bs which were crewed by two and bombed up to fly to Ocotal. Since there was no other Marine force in the area that could be delivered to the area in time on account of distance and Nicaragua's primitive transportation network, it was Marine air or nothing to save the garrison at Ocotal. Arriving over the garrison, Rowell circled the area to assess the situation. At the time, radios were supplied to VO-1M, but their were so heavy given the technology of the time, it was easier to remove the radios and trade that weight for fuel and bombs. The beleaguered Marine garrison laid out colored panels to give Rowell and his pilots indications of where the Sandinistas were located. Being 125 miles from their base in Managua, the fuel situation didn't lend itself to extended loitering by the DH-4Bs and to make matters worse, thunderstorms were approaching the area. Rowell organized his pilots into a bombing column that was single file and he made the first diving attack from 1500 feet, released a some bombs and then pulled out at 600 feet with the other four aircraft in the column following suit against targets he'd marked with his own bombs. Since the Sandinistas' previous exposure to air attacks were minimal, the Marine attacks drew little if any ground fire. In fact, the Sandinistas weren't even taking cover. Rowell astutely realized this fact and had his men fly lower for greater accuracy, diving from only 1000 feet and pulling out at only 300 feet. During their dives, the pilots fired the forward gun to add to the firepower and in the pull out, the observer in the rear seat would strafe as well with their trainable gun, effectively suppressing any potential ground fire. The Sandinista attack on the garrrison was broken as they retreated in the countryside taking approximately 25% casualties from the air attacks. Major Rowell would earn the Distinguished Flying Cross for leading the attack to save the Marine garrison at Ocotal.

It was a watershed moment in the history of military air power and close air support- the 1927 Battle of Ocotal was the first time that an ground unit facing a numerically superior enemy was saved solely by aerial intervention. It was a lesson not lost by the Marines in particular. During the time period and well into the Second World War, Army doctrine manuals discouraged close air support out of a fear of friendly fire casualties while the Marine Corps were quite the opposite in seeing air support as an integral part of ground force operations. It was also the first time that steep diving attacks were used in combat effectively. During his time at North Island in San Diego, Rowell had made friends with a number of naval aviators of the Pacific Fleet would were soon to make their own mark on the history of military aviation with their use of dive bombing. But as always, that will be the subject of a future post on this blog!

Historical aside: VO-1M was formed in 1919 as First Division, Squadron 1. Following the intervention in Santo Domingo, the squadron was redesignated VO-1M. Prior to the Battle of Ocotal, the squadron was redesignated again as VO-8M. In 1934, as part of the reorganization of Marine aviation, the unit was reorganized and was routinely sent to sea aboard aircraft carriers to participate in exercises. In 1941 the unit was moved to Hawaii with their first monoplane, the Vought SB2U Vindicator, along with a redesignation to VMSB-231 (Marine Scout and Bombing Squadron 231) and was embarked on the USS Lexington when Pearl Harbor was attacked. In 1942 the squadron transitioned to the Douglas SBD Dauntless and participated in actions at Guadalcanal and later in the war got the Vought F4U Corsair for the Marshall Islands campaign. They were deactivated in 1962 after long serving as a Marine reserve unit. They were brought back in 1973 to become an AV-8A Harrier unit and fly the AV-8B Harrier II today as VMA-231 "Ace of Spades"- the Ace of Spades logo used on VO-1M's DH-4s in Nicaragua are still the unit emblem today.

Source: Strike From the Sky: The History of Battlefield Air Attack, 1911-1945 by Richard P. Hallion. Smithsonian History of Aviation Series, Smithsonian Institution, 1989, pp 71-75. Photos: USMC, Wikipedia.