Clark County, Missouri's first northern border county, was organized in 1836 and named for explorer William Clark. In 1839, Iowa Territory and the State of Missouri mobilized troops on the nearby border in a boundary dispute called the Honey War over bee trees in the area, but compromise averted hostilities. In 1851, the Supreme Court set the Missouri-Iowa boundary at the old 1824 Iowa, Sauk and Fox Indian Purchase Line. The county was the site of the Battle of Athens on Aug. 5, 1861, one of the two northernmost Civil War skirmishes; there about 500 Union troops under Col. David Moore routed some 800 pro-Southern guards under Col. M.E. Green to save Iowa from Civil War action. The Anti-Horse Thief Association was first organized by David McKee at Luray in 1854 to curb frontier banditry through the capture and legal prosecution of criminals, and after its revival in 1863 the society had over 40,000 members in 11 states by the early 1900's; in 1926, the word "Horse" was dropped from the name. Clark County lies in a glacial plains region of rolling hills, dense woodland, and rich prairies, and near the mouth of the Des Moines the Mississippi begins its measure of Missouri's eastern boundary. The first settlers, largely Southerners, established St. Francisville on the Des Moines in 1829. During the Black Hawk War in 1832, Missouri troops built Fort Pike nearby when it was feared that the Iowa, Sauk, and Fox Indians might invade land once theirs. Kahoka, the county seat since 1872, was laid out in 1856 and named for the Cahokia Indians; earlier county seats were Waterloo and Alexandria. Near the mouth of the Des Moines, Alexandria once rivaled St. Louis as a pork packing center, processing 42,557 hogs in its peak year of 1870. Clark County also includes Kahoka, associated with David McKee, Athens, where marks of the Civil War battle remain, and St. Patrick, home to the church of the National Shrine of St. Patrick.