Complex sentence: His stay in New York ended when his work prospects ran out due to the economic slump occassioned by the outbreak of the Civil War he returned to London and thus to Paris where he died a few years later in extreme poverty.
Split into simpler sentences: His stay in New York ended when his work prospects ran out due to the economic slump occassioned by the outbreak of the Civil War. He returned to London and then to Paris where he died a few years later in extreme poverty.