John Henry Devereux was originally employed as a construction engineer on the Cleveland, Columbus and Cincinnati Railroad. After its completion he found similar employment on the Cleveland, Painesville and Ashtabula Railroad.
In 1852 he went south, and, until 1861, was engaged as civil engineer in the construction of railroads in Tennessee.
In the spring of 1862, after having made a reconnoissance for a military railroad in the Shenandoah Valley, Devereux received the appointment of superintendent of military railroads in Virginia, and under it had charge of all railroads out of Alexandria. It was early in the spring of 1862 that the forward movements of the Federal armies in Virginia called for active operation, by the government, of the railroad lines centering in Alexandria and connecting with Washington. These lines of railroads were in the most deplorable condition, and in the midst of chaos, and of imperative demands for endless transportation to and from the advancing armies, General McCallum was suddenly called to the head of the department of railroads, and in turn summoned Colonel Devereaux to act as the controller and chief of the Virginia lines. Devereux successfully rehabilitated the lines, making Alexandria a reliable transportation hub during the war.
In the spring of 1864, Devereux's military railroad work was drawing to a close, so he resigned his position, moved to Ohio and took a management position with the Cleveland and Pittsburg Railroad. In 1866 Devereux was invited to become vice president of the Lake Shore Railroad Company, and soon after accepting that position he was elected to the presidency. When the consolidation of the Lake Shore Road with the connecting lines between Buffalo and Chicago was effected, under the name of the Lake Shore and Michigan Southern Railroad Company, he was appointed general manager, and had executive control of this great line with all its connections and branches.
In June 1873, Devereux received overtures from the Atlantic and Great Western and the Cleveland, Columbus, Cincinnati and Indianapolis railroad companies. He accepted and held, at the same time, the position of president of both the companies.
Although never a politician, Devereux always manifested an active interest in public affairs. Twice he was tendered a nomination to Congress, but declined on both occasions.