Complex sentence: When Army Airship operations were terminated in 1937, a number of Army blimps were transferred to the USN, but only two, the TC-13 and 14 were ever operated by the Navy.
Split into simpler sentences: When Army Airship operations were terminated in 1937 a number of Army blimps were conveyed to the USN. Only TC-13 and 14 were operated by the Navy.