Because the Union victory opened the way to the control of the Tennessee River, which, together Fort Donelson on the Cumberland River represented the gateways for the invasion of Tennessee State.
The line of the River Ohio, with its tributaries Cumberland and Tennessee
Siezing control of the Mississippi River was an important goal of the Union Navy because it was the major means of transportation and logistical communications in the U.S. interior.
To have control of the boats and trade.
It gave the Union army control of the Mississippi River (apex)
It helped the Union gain control of the Mississippi River.
The Tennessee River and the Cumberland River were used by General Grant in the Union campaign.
That would be the Siege of Vicksburg.
The Mississippi River was important because if captured, it would divide the South making it weaker.
Because its conquest gave to Union the control of the Tennessee River.
It gave the Union army control of the Mississippi River
It helped the Union gain control of the Mississippi river.