Complex sentence: Later, Jensen introduces Mallory to a Partisan General called Vukalovic who commands the Partisans in the Neretva valley, who are trapped between the Neretva river to the south and east and impassable mountains in the north and west, in the so-called Zenica Cage.
Split into simpler sentences: Later, Jensen introduces Mallory to a Partisan General called Vukalovic. Jensen explains that Vukalovic commands the Partisans in the Neretva valley, who are now trapped against the Neretva river to the south and east and impassable mountains in the north and west, in the so-called Zenica Cage.