Complex sentence: Robert Hale Merriman (1908-1938) was an American professor of economics at the University of California who joined the Republican forces in Spain during the Spanish Civil War and commanded the Abraham Lincoln Battalion of the International Brigades.
Split into simpler sentences: Robert Hale Merriman (1908-1938) was an American professor of economics at the University of California. He joined the Republican forces in Spain during the Spanish Civil War and commanded the Abraham Lincoln Battalion of the International Brigades.