Played leading roles in the presidential campaigns of Richard M. Nixon and Gerald R. Ford and served as secretary of the Army under both.
Mr. Callaway, known as Bo, had a long and varied professional life that included helping to develop Callaway Gardens, a vast azalea garden and resort in rural Georgia, and buying and expanding Crested Butte Mountain Resort in Colorado. His career in politics was comparatively short; he held elective office for just one term in the House, representing Georgia from 1965 to 1967. But he helped Republicans rise in the South in the 1960s and ’70s.
When he was elected to the House in 1964, he became the first Republican to represent Georgia since Reconstruction, and he spent much of his time in office fighting civil rights bills.
Two years later, he ran for governor. Although he won a plurality of votes, he lost to the Democratic candidate, Lester G. Maddox, a strident segregationist.
May 1973, Nixon nominated Mr. Callaway to become Army secretary. In that post, he oversaw troop reductions as the Vietnam War was ending and dealt with the transition to a volunteer Army. After Nixon resigned in the wake of the Watergate scandal in 1974, Mr. Callaway stayed on under Ford, Nixon’s successor, who enlisted him in his own presidential campaign.
Mr. Callaway moved to Colorado in the 1970s and in 1980 ran unsuccessfully for the Republican nomination for Senate. The Republican candidate, Mary Estill Buchanan, the Colorado secretary of state, lost to the Democratic incumbent, Gary Hart.
He graduated from West Point in 1949 with a degree in military engineering, and served in the Korean War and was discharged in 1953.
He spent the next decade helping his parents, Cason and Virginia Callaway, develop Callaway Gardens, a 6,500-acre resort in Pine Mountain, near the Alabama border. Initially built to preserve azalea species, it now has golf courses and other attractions.
Elected as a Republican to the Eighty-ninth Congress (January 3, 1965-January 3, 1967); was not a candidate for reelection to the Ninetieth Congress in 1966
His survivors include two daughters, Elizabeth Considine and Virginia Martin; three sons, Howard Jr., Edward and Ralph; 16 grandchildren; and five great-grandchildren. His wife of 60 years, the former Elizabeth Walton, died in 2009.