John J. Hardin, a native of Kentucky who moved to Jacksonville in 1831 at age twenty-one, shared with Abraham Lincoln service in the Black Hawk War and careers as lawyers and Whig politicians, becoming rivals for leadership of their party while serving together in the Illinois House of Representatives for six years. In 1842, after Lincoln published a letter mocking General James Shields, a Democrat and Illinois State Auditor, Shields demanded satisfaction and Lincoln proposed using broadswords, but Hardin went to an island near Alton before the duel began and persuaded the men to compromise. The next year Lincoln jokingly asked Hardin in a letter to measure one of the swords they had taken to Alton. Hardin was killed on February 23, 1847, at the battle of Buena Vista in the Mexican War, and his funeral in Jacksonville drew 15,000 mourners, one of the largest gatherings in Illinois before the Civil War; Lincoln said that in Hardin's fall, the Whigs had lost their best man. Hardin, who was also Mary Todd Lincoln's cousin and friend, helped bring Abraham Lincoln and Mary Todd back together after their broken engagement when he and Sarah Hardin invited them separately to their home on East State Street after a Jacksonville wedding in late September 1842, leading to their reconciliation and marriage on November 4, 1842.