A question occurred to me that I've never researched. What had U.S. Grant anticipated for time, casualties and forces need to invest and capture Forts Donelson & Henry?

Had Grant anticipated a need for a longer siege and the need for a larger force? If the Confederates would've decided to try and holdout a little longer, did Grant have support troops available, how many and which ones? With a longer siege, how likely was a rescue mission by A.S. Johnston, in your opinion?

Just curious and hoping some on this board have researched or pondered these questions.

Thanks,

Jim