Son of William and Elizabeth (Hathaway) Rennie, of Pittsfield, Massachusetts, Zenas was a merchant prior to his being commissioned as an officer during the Civil War. Rennie was quite zealous in helping to raise company I of the 49th Massachusetts Infantry, and, as such, was described thus, in the regimental history: "If he shows as much energy and perseverance in coomanding as he has in raising his company, he will be one of our very best officers," and it was also mentioned that "Captains Rennie and Weston have not only saved the Forty-ninth from being smothered in the birth, but they have also saved the county the unpleasantness and dishonor of a draft." Rennie's family had been quite well known in Pittsfield, and, when he entered the Union Army in October, 1862, he commanded company I. He was, at the review of the regiment by the governor of Massachusetts, in October, 1862, presented with a sword, sash and belt by the family of state government official, Zenas Crane, whose name he had been given, at birth. Rennie was also presented with a Smith and Wesson's revolver, at the parade. The unit later operated in Louisiana, and were involved in the campaign against Port Hudson, in mid 1863, and were, after the fall of the town, sent on to Baton Rouge and then home to Massachusetts, to be mustered out. Rennie was reputed to be a crack shot, and an account is given of his assisting, with other sharpshooters of the unit, to silence a Confederate artillery battery, which had been annoying them. Also, mention is made of Rennie having been grazed by a Confederate bullet, losing his cap, and a lock of his hair, in the process. After his service he was appointed as Assistant State and Allotment Commissioner, and, after the war, held the position of cashier at Providence, Rhode Island, and also worked with his father, producing medicinal oil. After the business was sold, Zenas then took up the occupation of an insurance agent in Providence, Rhode Island, and later at Springfield, Massachusetts. Resided as a life insurance agent, in 1870, with his first wife, Margaret, and son Harry, at Providence, Rhode Island. He was a marshal, in 1870, of the Masonic, Corinthian Lodge No. 27, of Rhode Island. Resident, as a general insurance agent, in 1880, with wife, Margaret, and two sons, at Springfield, Massachusetts. It is not known if his first wife was deceased, or if they had separated, when he married Mary E. Warner, his second wife, at Massachusetts, on March 12, 1885. Later, with the Mutual LIfe Insurance Company of New York, he was sent to Australia, as the manager of the Sydney office, arriving in that city on his birthday, October 27, 1886. He continued in this position until his retirement in 1904, and then, very shortly after, returned to the United States, settling in San Francisco. After his property in that city was destroyed in the famous earthquake, he returned to Australia, where he remained until his death in Sydney. He was a member of the Masons, as well as other organisations, including the Military Order of the Loyal Legion of the United States. Zenas C. Rennie was the author of at least two publications, one being "The Benefactor" published at Providence, Rhode Island, in 1869, and the second, written jointly with William Paley Steward, under the title "A Social Event" published by Sands and McDougall, at Sydney, New South Wales.
[From the original research of the late Roy Parker, as well as Barry Crompton, of Melbourne, Bob Simpson of Beechworth, Len Traynor of Sydney, and Terry Foenander, and published in the volume, CIVIL WAR VETERANS IN AUSTRALIA.]