Henry David Thoreau and Ralph Waldo Emerson made major contributions to American thought. Members of the Transcendentalism movement, they emphasized the importance of the natural world and emotion to humanity. Although significant opposition to abolitionism existed early on in Massachusetts, resulting in anti-abolitionist riots between 1835 and 1837, opposition to slavery gradually increased in the next few decades. Famed abolitionist John Brown moved to the ideologically progressive town of Springfield in 1846. It was there that Brown first became a militant anti-slavery proponent. In Springfield and in Boston, Brown met the connections that would both influence him, (Frederick Douglass and Sojourner Truth in Springfield,) and later fund his efforts, (Simon Sanborn and Amos Adams Lawrence in Boston,) in Bleeding Kansas and John Brown's raid on Harpers Ferry. In 1850, Brown founded his first militant, anti-slavery organization – "The League of the Gileadites" – in Springfield, to protect escaped slaves from 1850s Fugitive Slave Act. Massachusetts was a hotbed of abolitionism – particularly the progressive cities of Boston and Springfield – and contributed to subsequent actions of the state during the Civil War. Massachusetts was among the first states to respond to President Lincoln's call for troops. Massachusetts was the first state to recruit, train, and arm a Black regiment with White officers, the 54th Massachusetts Volunteer Infantry. The Robert Gould Shaw Memorial in Boston Common contains a relief depicting the 54th regiment. Much of the Union's weaponry for the Civil War was produced in Springfield, at the Springfield Armory.