Weaver traveled around southern Iowa in 1858, giving speeches on behalf of his new party's candidates. That summer, he married Clarrisa (Clara) Vinson, a schoolteacher from nearby Keosauqua, Iowa, whom he had courted since he returned from Cincinnati. The marriage lasted until Weaver's death in 1912 and the couple had eight children. After the wedding, Weaver started a law firm with Hosea Horn and continued his involvement in Republican politics. He gave several speeches on behalf of Samuel J. Kirkwood for governor in 1859 in a campaign that focused heavily on the slavery debate; although the Republicans lost Weaver's Davis County, Kirkwood narrowly won the election. The next year, Weaver served as a delegate to the state convention and, although not a national delegate, traveled with the Iowa delegation to the 1860 Republican National Convention, where Abraham Lincoln was nominated. Lincoln carried Iowa and won the election, but Southern states responded to the Republican victory by seceding from the Union. By April 1861, the American Civil War had begun.