In 1879, Haskin authored a book, History of the First United States Artillery. In 1881, Haskin was assigned to the Pacific coast, and he performed artillery duty at several posts in California, and commanded the 1st Artillery's Battery H and Battery K. He was promoted to major on August 11, 1887. In 1888, he was assigned as inspector general and inspector of rifle practice for the Department of California. In 1889, he served on an Army board that conducted reconnaissance of several California ports in order to make recommendations for defending them with coast artillery. From July to September 1889, Haskin commanded a light artillery battalion during a summer training encampment in northern California. He was then posted to Fort Alcatraz, where he remained until returning to duty in the eastern United States.
