Most professional militaries employ specialised military nurses or nursing sisters. They are often organised as a distinct nursing corps. Florence Nightingale formed the first nucleus of a recognised Nursing Service for the British Army during the Crimean War in 1854. In the same theatre of the same war, Professor Nikolai Ivanovich Pirogov and the Grand Duchess Yelena Pavlovna originated Russian traditions of recruiting and training military nurses – associated especially with besieged Sevastopol (1854–1855). Following the war Nightingale fought to institute the employment of women nurses in British military hospitals, and by 1860 she had succeeded in establishing an Army Training School for military nurses at the Royal Victoria Military Hospital in Netley, Hampshire, England.

In 1898, after the Spanish-American War, the United States added 1,500 nurses to their military personnel (Brooks, 2018). A year later in 1899, the Surgeon General recognized the importance of these nurses and established a "reserve group" of nurses with specific criteria to prepare for future wars. Military nurses are similar to floor nurses in that they spend most of their time providing direct patient care. Patient assessments, medication distribution, interventions and documentation are part of their daily work. These nurses are needed at all military bases, active war zones, clinics and front lines – not always on United States territory.