Complex sentence: Merritt began making plans with Dewey regarding the capture of the city and the two purposefully left Aguinaldo out of any of the plans and preparations even though his forces would have doubled the total American ground forces.
Split into simpler sentences: Merritt began making plans with Dewey regarding the capture of the city. The two had purposefully left Aguinaldo out of any of the plans and preparations even though his forces would double the total American ground forces.