What supports this passage is that Texas and California were under control by Mexico until the land was fought for. That is why America couldn't annex it.
The Ottomans conquered it adding power to their empire.
Most black soldiers were scattered throughout the Continental Army in integrated infantry regiments, where they were often assigned to support roles as wagoners, cooks, waiters or artisans. African Americans also served as gunners, sailors on privateers and in the Continental Navy during the Revolution.
African-Americans fought for both sides, providing manpower to both the British and the revolutionaries.