Chapman was born on September 6, 1829, in Greensboro, Alabama. His grandfather, Robert Hett Chapman, was born in Orange, New Jersey, studied theology and was a pastor from 1796 to 1812, at which time he became president of the University of North Carolina at Chapel Hill until 1816. His father attended the University of North Carolina, but failed to graduate due to a cheating scandal. Alfred's maternal grandfather was a colonel in the United States Army. Chapman graduated 29th in his class at West Point in 1854. Upon graduation from West Point, Chapman was assigned to the First Regiment of Dragoons in Florida.
His various postings eventually brought him in the late 1850s to California. Chapman resigned from the army in 1859, having achieved the rank of major, and married Mary Scott, the daughter of a prominent Los Angeles attorney. He studied law with her father, Jonathan R. Scott, and was admitted to the bar in California.
In 1863 Chapman became city attorney of Los Angeles, and in 1868 he was elected district attorney of Los Angeles County. He went into partnership with a boyhood friend, Andrew Glassell, when the latter arrived in Los Angeles in 1866. Colonel George H. Smith, a former Confederate Army officer and brother-in-law of Glassell, joined the firm in 1870. Their law practice was confined chiefly to real estate transactions, and they made their fortunes by handling the large partition suits. Chapman was the businessman of the firm. He would take his compensation in land, and nearly every final decree in partition would find that Glassell & Chapman had acquired land.
Chapman and Glassell are best known in Orange County for being founders of Orange, California. The firm represented the Yorba and Peralta families in the partitioning of Rancho Santiago de Santa Ana in 1867, and had received for a portion of their fees certain large parcels of land in the partition. He joined with one of his partners, Andrew Glassell, to develop a new community, Richland (which would eventually be named Orange). They hired the land surveyor, Frank Lecouvrier of Los Angeles, to map this tract, which they called Richland Farm District. 'Richland' was originally the name of the Virginia plantation owned by the father of Andrew Glassell in the 1830s.
A large transaction by Chapman and Glassell was the legal suit known as "The Great Partition of 1871", brought against the Verdugo Rancho San Rafael properties on the Los Angeles River and in the Verdugo Mountains. The legal fees were again paid in substantial land transfers.
Chapman continued to practice law until 1880. After retirement, he devoted full-time to managing his 700-acre (2.8 km2) rancho in the upper San Gabriel Valley, a portion of the Rancho Santa Anita grant, and became involved in citrus production.
He had six children by his first marriage to Mary Scott. He married again after her death in 1883, and had one child by his second marriage to Mary L. Stephens, daughter of a pioneer California attorney and judge.
Chapman died at his residence on January 16, 1915.
- Alfred B. Chapman (1829-1915) City of Orange History
- Samuel Armor (1921) History of Orange County, California, Historic Record Co, Los Angeles
- James Miller Guinn (1915) A History of California and an Extended History of Los Angeles and Environs
- District Attorney 1863-1864 & 1867-1869
- Rancho San Rafael