In the Senate, James Murray Mason of Virginia resolutely defended southern interests. On January 4, 1850, he introduced the Fugitive Slave Act to strengthen existing law regarding runaway slaves. Henry Clay included the measure in his Compromise of 1850, a set of resolutions aimed at diffusing the sectional crisis. Clay’s compromise faced stiff opposition, particularly from ailing South Carolina senator John C. Calhoun. On March 4, 1850, with the dying Calhoun too weak to speak, Mason rose in the Senate Chamber to read Calhoun’s final speech, denouncing the compromise. Eventually, the Senate approved five of Clay’s resolutions, including Mason’s Fugitive Slave Act. Although such measures maintained a fragile peace for a decade, ultimately they could not stave off civil war. On March 28, 1861, two weeks before the firing on Fort Sumter, Mason withdrew from the Senate to join the Confederacy. Four months later, on July 11, the Senate expelled Mason and nine of his southern colleagues. On November 8, 1861, the U.S. government arrested Mason and former senator John Slidell as they traveled to Europe to serve as diplomatic commissioners for the Confederacy, an incident known as the Trent Affair.