Complex sentence: Most of the armored and light cruisers saw action in all of the major theaters of World War I, including as commerce raiders in the open ocean and in the fleet engagements in the North Sea such as the Battle of Jutland.
Split into simpler sentences: Most of the armored and light cruisers saw action in World War I, in all of the major theaters of the conflict. Their service ranged from commerce raiding patrols on the open ocean to the fleet engagements in the North Sea such as the Battle of Jutland.