Warren County is Butler County's eastern neighbor and was formed by the Ohio General Assembly at the same time. Ohio became the 17th state March 1, 1803, and 23 days later, March 24, the Ohio General Assembly passed an act "for the division of the counties of Hamilton and Ross," forming eight new counties: Gallia and Franklin, effective April 30, 1803, and Butler, Warren, Greene, Montgomery, Columbiana and Scioto, effective May 1, 1803. Warren County was taken from Hamilton County. The county was named for Major-General Joseph Warren (1741-1775), also a physician, who died in the Battle of Bunker Hill June 17, 1775, in Boston at the start of the American Revolution.
Jan. 20, 1808, a portion of Butler County, near the present City of Franklin, was switched to Warren County. That same date the boundary between Butler and Hamilton counties was moved north about a mile. March 1, 1808, Preble County (Eaton) was formed from Butler and Montgomery counties. March 1, 1815, another part of Butler County was transferred to Warren County (that part of Franklin Twp. including Carlisle). Beedle Station -- also known as Beedle's Station and Beedle's Blockhouse -- is regarded as the first frontier settlement in Warren County after the signing of the Greenville Indian Treaty in 1795. It's location was at about the present intersection of Ohio routes 63 and 741. (see separate entry for Beedle Station.) The town of Lebanon was laid out in September 1802 by Ichabod Corwin, Silas Hurin, Ephraim Hathaway and Samuel Manning. In 1803 Ichabod Corwin built the first Warren County courthouse, a log structure, known as Black Horse Tavern in Lebanon, which became the county seat Feb. 4, 1805. Lebanon was named for the Biblical Cedars of Lebanon. The Golden Lamb opened in 1803 in Lebanon. A Lebanon post office was established April 1, 1805, with William Ferguson as postmaster. Other early settlements included Deerfield (now South Lebanon) in 1795, and Waynesville and Franklin in 1796.
The four original townships, formed May 10, 1803, were Deerfield, Franklin, Wayne and Hamilton. The present 11 townships in Warren County are Franklin, Turtlecreek and Deerfield that border Butler County, and Hamilton, Union, Harlan, Salem, Washington, Massie, Wayne and Clear Creek. (See separate entries for Franklin, Deerfield and Turtlecreek township, Golden Lamb, Deerfield, Carlisle, Kings Mills, Kings Island, Mason, National Normal School, Middletown & Cincinnati Railroad and Warren County Canal.)