 Their goal was to occupy the towns of Angostura and Old Guayana, which would allow them to dominate traffic along the river Orinoco.Manuel Piar had taken the missions of Caroni in early 1817, which had served as an important supply base for the royalist Spanish forces; it would thereafter fill the same role for the revolutionaries.With the loss of the missions, the places held by the royalists were largely without a source to supply their armies & were at risk of hunger.