The english gained control of the valuable altamaha river by

The English gained control of the important Altamaha river because they built a special fortress called "King George Fort", the oldest building from that era remaining in Georgia.

Built in 1721, that Fort was the southern outpost of the English army and was led by Colonel John Barnwell.

Altamaha River –with its 470 miles long- flows into the Atlantic and is the 7th longest in the country for rivers that runs within one state and It’s the third largest contributor of fresh water to the Atlantic Ocean.

answer; /// the above statement is (true);