Complex sentence: Back home in France, the Revolution of 1848 now in full swing and King Louis Philippe overthrown, the necessity of emigration to achieve democratic ideals became less compelling and the volunteers for Icarian colonization in America melted away.
Split into simpler sentences: Back home in France, the Revolution of 1848 had long been in full swing and King Louis Philippe overthrown. The necessity of emigration to achieve democratic reforms seemed less compelling and the volunteers for Icarian colonization in America melted away.