[3] During 1913, the company operated the affiliated Thomas Brothers School of Aviation at Conesus Lake, McPherson Point in Livingston County, New York state[2][4] (taking a page from Glenn Curtiss, who did much the same at Keuka Lake).

In 1915, Thomas Brothers built T-2 tractor biplanes (designed by Benjamin D. Thomas, no relation to the brothers and also an Englishman, formerly of Vickers, Sopwith, and Curtiss,[1] and later the company's chief designer) for the Royal Naval Air Service[5] and (fitted with floats in place of wheels)[6] for the United States Navy as the SH-4.

[7] In 1916, the company won a contract from the United States Army Signal Corps for two aircraft for evaluation, the D-5.

[6] In January 1917, financial difficulties led to the company merge with Morse Chain Company (headed by Frank L. Morse), who was backed financially by H T Westinghouse,[7] becoming Thomas-Morse Aircraft Corporation, still based in Ithaca.

[2] The company then made an attempt at selling training biplanes to the United States Army and was successful with the S-4 trainer (which included a handful of S-5 floatplanes and a single S-4E) and MB series of fighters.