Complex sentence: The Siege of Humaitá was a prolonged operation of encirclement which occurred at the Fortress of Humaitá, on the Paraguay River, beginning on 2 November 1867, as a part of the Paraguayan War, and ending on 25 July 1868.
Split into simpler sentences: The Siege of Humaitá was a prolonged operation of encirclement that occurred at the Fortress of Humaitá, on the Paraguay River. It began on 2 November 1867 as a part of the Paraguayan War and ended on 25 July 1868.