Although he held many notable posts during his military career, he is most well known for his service on the western frontier of the United States and in Cuba.

In the summer of 1881, he accompanied an exploring expedition into northwest Texas, headed by Captain William R. Livermore, Corps of Engineers.

From stations at Fort Duncan and San Antonio, he again went with exploring parties under Captain Livermore to the upper Rio Grande Valley during the summers of 1883 and 1884.

While on frontier duty, he became interested in economic botany and studied the food and drink plants of the Indians, Mexicans, and early settlers.

[2] With the establishment of civil government in Cuba, Colonel Havard returned to the United States for duty in Virginia (Fort Monroe) and New York (West Point and Department of the East at Governors Island).

According to Havard, the result of these trends was soldiers experiencing an increased level of battle fatigue, as well as resurgence in the usefulness of the bayonet in night assaults.

Because of the increased number of casualties resulting from modern weaponry, Havard stressed the significance of training enlisted soldiers in assisting medical officers in field hospitals.

Havard's early articles were on botany and military hygiene, continued with reports on observations on the Spanish-American and Russo-Japanese Wars.

He won the Enno Sander prize given by the Association of Military Surgeons in 1901 with an essay on "The Most Practicable Organization for the Medical Department of the United States Army in Active Service".

He published a number of articles on the flora of Montana, North Dakota, Texas, and Colorado, including "Botanical Outlines" in Report of the Chief of Engineers, Part III (1878), and "Report on the Flora of Western and Southern Texas" in Proceedings of the United States National Museum (1885).