O.P. Amacker was born in St. Helena Parish, LA, the son of Nathaniel (1811-1881) and Mosilla (Pearson) Amacker (1813-1871). Amacker studied law at the University of Virginia in sessions 35-36 (1858-1860), then studied law in New Orleans, LA. In 1861, he enlisted in the Confederate Army, rose in rank from orderly sergeant to lieutenant, and finally served as Lieutenant Colonel of the 3rd Regiment, Louisiana Cavalry. He was captured by the Federal forces at Port Hudson, LA, in 1863, and was imprisoned at Johnson Island, Ohio and in Baltimore, MD until he was exchanged in 1864. After the surrender, he was paroled at Gainesville, AL. Following the war, Amacker practiced law in Greensburg, LA.
Amacker married Abigail Means Kent (1841-1910) on 1 Sept. 1864. Their children were: Amos Kent, Samuel Hezekiah, Susan, Leslie Maud, Alice Means, Obediah Pearson Jr., Robert Percy, and Walter Kent Amacker. He is buried at Woodland Cemetery, Kentwood, in Tangipahoa Parish, LA.
- Booth, Andrew B., comp. Records of Louisiana Confederate soldiers and Louisiana Confederate Commands. New Orleans, LA, 1920.
- McDaniel, Matthew F. K. Kent-Amacker Family Papers, Mss. 4185, Inventory. Louisiana State University Libraries, 2009. http://www.lib.lsu.edu/special/findaid/4185.pdf (Accessed 4/19/2011)
- Tombstone of Obadiah Pearson Amacker. Findagrave.com [website]. (Accessed 4/19/2011).