"Fort Donelson was ultimately indefensible also. I believe Grant gets too much credit for this victory that could have been avoided by more prudent leadership from the Confederate command."

I agree.

I am not a fan of Grant. But to use the mistakes of your enemy to your advantage is not a vice. Ultimately Kentucky and most of central Tennessee was not defensible. But that does not change the situation that the Confederates high command mismanaged the situation and were spread too thin in too many places to mount an effective counter to Grant. The idea of fixed fortifications such as Henry and Donelson being able to hold certain areas was a lesson that was to be learned in 1861.

Forrest excaped from Donelson and was at Shiloh to fight there. What if all those prisoners which were at Camp Douglas and other POW camps from Donelson had been there also?

The Battles of Forts Henry, Donelson, and Island #10 were the first to demonstrate that the War between the States was to be a war of manuver rather than a war of reducing fixed positions. This was something that Lee developed later in the war. But Lee wasn't in command of any army in February, 1862.

I am amazed by the large amounts of heavy artillery abandoned in fixed fortification along the upper Mississippi river in places like Forts Pillow and Thompson and others emplacements, north of Memphis, after Forts Henry and Donelson and the fall of Island #10 that never fired a shot in anger because the Confederates couldn't remove them.