Complex sentence: This book was written by Friedrich Engels in London, during the summer of 1850, following the failure of the revolutions of 1848-1849, drawing a parallel between that failure and that of the Peasants' War of 1525.
Split into simpler sentences: This book was written by Friedrich Engels in London, during the summer of 1850, following the revolutionary uprisings of 1848-1849. The book draws a parallel between the uprisings of 1848-1849 and the Peasants' War of 1525.