How would a government legally take control of another territory to add to its own

A government can legally take control of another territory by CESSION

Explanation:

Cession is the surrender or assignment of a territory under the control of a country or state to another country or state. this done as a repayment of debt been owed or as a former of surrender or as part of a peace treaty. cession is documented legally and agreed to by both parties i.e the country giving up its territory and the country/state receiving it. Example is the cession of New mexico to the USA by Mexico after the war

Annexation is also a means of taking another territory by a country. this is mostly done through Military invasions and hence it is not a legal means  example of such is the Nazi Germany annexing Austria through military invasion.

d. promised it other land

in 1862, president lincoln's emancipation proclamation opened the door for african americans to enlist in the union army. although many had wanted to join the war effort earlier, they were prohibited from enlisting by a federal law dating back to 1792.

explanation: