The Kansas-Nebraska Act of 1854 allowed the settlers in the Kansas-Nebraska territories to determine whether they wanted slavery or not by popular sovereignty (the vote of the people themselves). Pro- and antislavery groups in Kanasa set up separate constitutions and rival governments at Lecompton and Topeka respectively (1855). The murder of an antislavery man in November 1855 brought on the so-called Wakarusa War, a series of clashes between pro and antislavery forces along the Wakarusa River near Lawrence, Kansas (November 26-December 7, 1855). A few casualties occurred, and armed proslavery Missourians, called "border ruffians," made plans to attack Lawrence, Kansas, which was defended by Free-Soilers (opponents of the extension of slavery in the western territories). The attack and the "war" itself were aborted by the intervention of the territorial governmor. In 1856, border ruffians did raid Lawrence, causing a retaliatory attack by abolitionists on the settlers at Pottawatomie Creek [the Pottawatomie Massacre]. Hostilities between free and slave interests erupted into civil war, referred to as "bleeding Kansas," which lasted until federal troops and restored order in 1860.