Marion G. Merrill, 97, a civil rights activist and writer, died of heart ailments Feb. 16 at Cokesbury Village retirement community in Hockessin, Del., where she had lived since 1988. The death was confirmed by Donald A. Ritchie, a friend of the family.

Mrs. Merrill was the widow of Horace Samuel Merrill, a professor of history at the University of Maryland. She was co-author with him of a 1971 book, “The Republican Command, 1897-1913.” They had been married for 53 years when he died in 1996. Mrs. Merrill also helped her husband in the mentoring of graduate students....