The Martin Baltimore was a light bomber developed by the Glenn L. Martin Company from its Model 167 Maryland to satisfy a British specification. The RAF had inherited the Maryland from an original French order, and had eventually purchased 225 aircraft. British interest in the Martin Model 187 actually predated their first use of the Maryland – the first contract for Baltimores was signed in May 1940, while the RAF did not get its first Maryland until late June 1940, after the fall of the France.
The RAF eventually placed three orders for the Baltimore. The first, for 400 aircraft and placed in May 1940, resulted in the delivery of 50 Baltimore Is, 100 Baltimore IIs and 250 Baltimore IIIs. The second, for 575 aircraft, was placed in June 1941 and produced 281 Baltimore IIIAs and 294 Baltimore IVs. The final order, for 600 aircraft, was placed in July 1942. All 600 aircraft were delivered as Baltimore Vs.
The Baltimore had the same wingspan as the Maryland, and was only slightly longer, but had a wider and deeper fuselage, giving the four-strong crew a limited ability to move between the three crew positions (the fuselage was still too narrow for easy movement). The Baltimore I carried four more guns than the Maryland, with four fixed Browning machine guns in the wings, one each in the dorsal and ventral positions and four fixed guns fixed to fire downwards and to the rear. The Baltimore was powered by 1,660hp Wright GT-2600 engines, which more than made up for the increase in weight, and gave it a top speed of just over 300mph and the capability to carry 2,000lb of bombs. The Baltimore was the second most numerous Martin aircraft, after only the B-26 Marauder. It was given the American designation A-30, but never entered USAAF service.
The first Baltimore Mk I reached the UK in October 1941, and underwent trials at Burtonwood near Liverpool. It entered service three months later, in January 1942, with No.223 Squadron at Shandur, Egypt. At the time this was an Operational Training Unit, but it would soon take its Baltimores into combat. The first operation unit to get the Baltimore was No.55 Squadron, also in Egypt, in May 1942. This established a pattern which saw the Baltimore used exclusively in the North African and Italian theatres.
The dorsal guns on the early models of the Baltimore soon proved to be troublesome, and were blamed, perhaps unfairly, for heavy losses suffered in an early mission on 23 May, in which four unescorted Baltimores were all shot down by eight Bf 109s. The existing aircraft all had their American Brownings replaced by British equivalents on a different mounting, and unescorted missions came to an end.
The Baltimore’s combat debut came just before the final German advance of the war in North Africa, which brought Rommel to El Alamein. The Baltimore played an important part in the fighting before the Second battle of El Alamein, operating in “boxes” of 12-18 aircraft. The increasing Allied dominance of the skies over North Africa allowed these boxes to operate with heavy fighter escort, and prevented the German fighters from interfering with their attacks on the German rear areas.
The Baltimore remained in constant use as a bomber and reconnaissance aircraft in the Mediterrean throughout the rest of the campaign in North Africa, during the invasions of Pantelleria, Sicily and Italy, and during the campaign on the Italian mainland. It was also used by No.13 Squadron of the Royal Hellenic Air Force, which operated over the Aegean and the Balkans before returning to Greece as the Germans pulled out.
The number of Baltimore squadrons peaked at eleven in 1944 (No.500 and No.249 Squadrons were actually the same unit, which changed numbers in 1944), but had halved by the end of the year. No single aircraft replaced the Baltimore, and squadrons which had been equipped with it transferred to the Boston (two squadrons), Dakota, Mosquito (two squadrons), Wellington (two squadrons), Liberator and Marauder