One of the wealthiest and most cultured residents of the famed Algonquin Avenue in Buffland (a city intended to be Cleveland), Captain Arthur Farnham is a Civil War veteran and widower—his wife died of illness while accompanying him at a remote frontier post. Since he left the army, he has sought to involve himself in municipal affairs, but fails though political naiveté. The victorious party has allowed him the position of chairman of the library board. In that capacity, he is approached by Maud Matchin, daughter of carpenter Saul Matchin, a man content with his lot. His daughter is not, and seeks employment at the library as a means of bettering herself. Farnham agrees to put her case, but is defeated by a majority on the board, who have their own candidate. She finds herself attracted to Farnham, who is more interested in Alice Belding, daughter of his wealthy widow neighbor.
Saul Matchin had hoped that his daughter would become a house servant, but having attended high school, she feels herself too good for that. She is admired by Saul's assistant Sam Sleeny, who lives with the Matchins, a match favored by her father. Sleeny is busy repairing Farnham's outbuildings, and is made jealous by interactions between the captain and Maud. Seeing Sleeny's discontent, Andrew Jackson Offitt (true name Ananias), a locksmith and "professional reformer", tries to get him to join the Bread-winners, a labor organization. Sleeny is happy with his employment, "Old Saul Matchin and me come to an agreement about time and pay, and both of us was suited. Ef he's got his heel into me, I don't feel it," but due to his unhappiness over Maud, is easy game for Offitt, who gets him to join, and to pay the dues that are Offitt's visible means of support.
Maud has become convinced that she is in love with Farnham, and declares it to him. It is not reciprocated, and the scene is witnessed both by Mrs. Belding and by Sleeny. The widow believes Farnham when he states he had given Maud no encouragement, but her daughter, when her mother incautiously tells her of the incident, does not. When Farnham seeks to marry Alice, she turns him down and asks him never to renew the subject.
Offitt's membership has tired of endless talk, and plans a general strike, a fact of which Farnham is informed by Mr. Temple, a salty-talking vice president of a rolling mill. An element among the strikers also plans to loot houses along Algonquin Avenue, including Farnham's. The strike begins, paralyzing Buffland's commerce, though it is initially nonviolent. Neither the mayor nor the chief of police, when approached by Farnham, are willing to guard Algonquin Avenue. Farnham proceeds to organize Civil War veterans, and purchases weapons to arm them. After Farnham's force rescues the mayor from being attacked, he deputizes them as special police—on condition there is no expense to the city.
Meanwhile, Maud tells her father she will never marry Sleeny. She is wooed by Bott, who is a spiritualist and a Bread-winner, and also by Offitt. Neither meets success, though Offitt dexterously prevents her from actually saying no, and through flattery and stories of his alleged past piques her interest.
By the end of the second day of the strike, which has spread to Buffland's rival city of Clearfield [in the serialization, "Clevealo"], the mood among the laborers has turned ugly. Temple warns that the attacks on Algonquin Avenue are imminent, and aids Farnham's force in turning back assaults on the captain's house and on the Belding residence. Bott and Sleeny are captured by the force; the former is sent to prison but Farnham has pity on Sleeny as a good workman, and the carpenter serves only a few days. The settlement of the strike in Clearfield takes the wind out of the Buffland action, and soon most are back at work, though some agitators are dismissed.
Offitt, despite being one of the leaders of the assault on the Belding house, has escaped blame and befriends the sullen Sleeny on his release. Upon learning that some workers pay their landlord, Farnham, in the evening of the rent day at his home, Offitt comes up with a scheme—rob and murder Farnham and let Sleeny take the blame as Offitt elopes with Maud. Accordingly, Offitt sneaks into Farnham's house with Sleeny's hammer, but just as he is striking the fatal blow, Alice Belding, who can see what is going on from her house through an opera glass, screams, distracting Offitt enough so that Farnham is hurt by the blow, but not killed. Offitt hurries away with the money, and proceeds to frame Sleeny. After realizing Offitt's treachery, Sleeny escapes jail and kills him. The stolen money is found on Offitt's body, clearing Sleeny in the assault on Farnham, but the carpenter must still stand trial for the killing of Offitt, in which he is aided by partisan testimony from Maud. A sympathetic jury ignores the law to find him not guilty. Sleeny wins Maud's hand in marriage, and Farnham and Alice Belding are to be wed.

Question: What war is Captain Arthur a veteran of?
Answer:  Civil War