With the outbreak of the Civil War, Coffin, moved by abolitionist fervor, volunteered for service and was assigned to the 32nd Iowa Infantry. He advanced rapidly up the ranks from private to sergeant, receiving special recognition for his bravery and leadership. Later he was appointed regimental chaplain.
After the Civil War, Coffin returned to farming. His farm, Willowedge, became one of the showplaces of progressive farming. He achieved great success in stock raising, introducing pure-bred varieties of hogs, sheep, cattle, and horses, and he was recognized for his efforts by being elected president of the Iowa Breeders Association.
In 1872 he became one of the first farm editors for a general newspaper in Iowa, the Fort Dodge Messenger. When Iowa organized farm institutes, Coffin was one of the first to travel around the state giving lectures on agricultural topics. When farmer began to organize politically, Coffin held leadership roles, first in local and state agricultural societies, and later in the Grange and farmer Alliance movements. He was instrumental in organizing farmer-related cooperatives: creameries, a farmer mutual insurance company, and a farmer-owned barbed wire factory.
Coffin's interests broadened when the state, in an attempt to attract settlers and to encourage economic growth, established an immigration board in 1870. Coffin was chosen as one of the board's first recruiting agents. In the 1870s he became a land agent for the Des Moines River Navigation Company and later for the Des Moines and Fort Dodge Railroad.
In 1883 he was appointed to the Iowa Railroad Commission. It was in this role that he first became aware of the safety problems that railroad employees faced. Railroading in the post-Civil War period was the nation's most hazardous occupation. According to Coffin, in 1881 alone more than 30,000 men were either killed or maimed in rail accidents. Coffin's personal observation of a brakeman losing his fingers in the act of switching cars led him to become a self-proclaimed spokesman for workers' interests. For 10 years Coffin spent much of his time trying to arouse the public to the extent of the problem. He lobbied for the adoption of state and federal safety legislation. A bill requiring automatic couplers and air brakes finally became law in 1893.
Coffin's railroad reforms did not stop with the safety laws. He advocated, without success, a Sunday no-work law; he organized the Railroad Men's Temperance Association; through his efforts a railroad men's retirement home was established in Highland Park, Illinois; and he worked to create a railroad men's Young Men's Christian Association (YMCA) as an alternative to the street life and saloons.
In the 1890s Coffin became interested in the problems of ex-convicts and unwed mothers. In 1901 he organized the Iowa Benevolent Association and, using his own funds, established Hope Hall, a halfway house for released convicts. In 1910 he established a home for young unwed mothers.
Coffin's reform interests naturally took him into politics. Like most Iowans of the time, he was a staunch Republican, but the party's failure to address some issues drew him to third parties. In 1907 he was the Prohibition Party's candidate for governor. The following year he was the nominee of the United Christian Party for vice president.
Lorenzo Coffin died on January 17, 1915. His burial site, a mile west of Fort Dodge, is on the National Register of Historic Places. (Natte, Roger. "Coffin, Lorenzo Stephen" The Biographical Dictionary of Iowa. University of Iowa Press, 2009. Web. 3 November 2013)