In June 1898, during the Spanish–American War, Hasson became a contract nurse with the U.S. Army, subsequently serving on the hospital ship Relief and in the Philippines.

When the Navy Nurse Corps was established in 1908, Hasson became its first Superintendent, taking the oath of office on 18 August 1908.

On March 8, 1942, Nurse Esther V. Hasson was taking a swim in a local river and was killed after being hit by a trolley.

The first nineteen nurses, in addition to Hasson, carefully chosen from 33 invited candidates, came to be known as the "Sacred Twenty".

Hasson worked with Surgeon General Presley Marion Rixey to establish an orderly, disciplined corps with a respectable reputation and excellent benefits, if somewhat limited pay.