The Model 187 met the needs for a light-to-medium bomber, originally ordered by the Anglo-French Purchasing Commission as a joint project in May 1940.

To enable the aircraft to be supplied to the British under the Lend-Lease Act the United States Army Air Forces designation A-30 was allocated.

Users of the Baltimore and Martin pilot Benjamin R. Wallace, praised the aircraft for its heavy armament, structural strength, manoeuvrability, bombing accuracy and relatively high performance but crews complained of cramped conditions similar to those in the earlier Maryland bomber.

The narrow fuselage made it nearly impossible for crew members to change positions during flight if wounded (the aircraft's interior structure separated the pilot and observer from the wireless operator and rear gunner, a characteristic shared with several light and medium bomber designs of that era e.g. Handley Page Hampden, Douglas Boston and Blenheim).

[3] Thrown into action to stop Rommel's advance, the Baltimore suffered massive losses when it was used as a low-level attack aircraft, especially in the chaos of the desert war where most missions went unescorted.

Undertaking a variety of missions in the Middle East, Mediterranean and European theaters, the Baltimore's roles included reconnaissance, target-towing, maritime patrol, night intruder and even served as highly uncomfortable fast transports.

Most Baltimores were scrapped soon after the war, although one RAF squadron continued to use the type in Kenya where the aircraft were used in aerial mapping and locust control until 1948.

In post-war service, the Baltimore took part in United States Navy instrument and control surface tests in the effort to break the sound barrier.