What roles did indentured servants & slaves serve?

In what context.

They were labor for their "owner".
- Indentured servants, however, usually were made to work for a certain amount of time so as to work off the debt incurred in bringing them over from wherever to America/etc. They worked until they were free of the debt, and if lucky then the person holding the "IOU" wouldn't tack more and more on.
- Most slaves were purchased and made to work until they were sold or died. Some, however, were also able to buy their freedom from their "owner".
Hope this helps.

Nixon believed his Vietnam strategy, which involved building up South Vietnam’s military strength in order to facilitate a gradual withdrawal of U.S. troops, would prepare the South Vietnamese to take responsibility for their own defense against a Communist takeover and allow the U.S. to leave the conflict with its honor intact.