In February, 1862, Ulysses S. Grant captured Fort Donelson in a little over a day. Most forts hold out for "many" days, especially when the ratio of attacking to defending forces is less than two to one (as was the case here).

Except that Fort Donelson was apparently peculiarly vulnerable to capture. One obvious vulnerability was the presence of Union gunboats on the Tennessee River. Was this only important vulnerability or were there others?

1 Answer 1


With Grant leading the assault force, a rarity of competence among the generals on both sides: 100% chance of falling on the 16th or perhaps 17th.

With 16,000 men to defend a roughly 2 mile defensive perimeter, the Confederates were fielding 8000 men per mile. Despite numbers seemingly prophetic of World War 1 the fort succumbed on the second day of assault.

The truth is that Fort Donelson was woefully unprepared for an overland assault; doomed to fall quickly to any competent, determined, and aggressive assault. Think Singapore in February 1942. There was no fallback position from the outer perimeter except retreat into the fort proper combined with surrender (or as attempted unsuccessfully, breakout) by 80% of the defensive force; but even that buys, at best, only a few extra days.

General Simon Bolivar Buckner, however, argued that they were in a desperate position that was getting worse with the arrival of Union reinforcements. At their final council of war in the Dover Hotel at 1:30 a.m. on February 16, Buckner stated that if C.F. Smith attacked again, he could only hold for thirty minutes, and he estimated that the cost of defending the fort would be as high as a seventy-five percent casualty rate. Buckner's position finally carried the meeting. Any large-scale escape would be difficult. Most of the river transports were currently transporting wounded men to Nashville and would not return in time to evacuate the command.

A properly prepared fort holds out for months instead of hours, as Mantua in 1796 (7 months), Genoa in 1800 (2 months), Mafeking in 1899-1900 (7 months), or Tobruk in 1941 (8 months). Note that the number of defenders above for all but Mafeking is not far off the 16,000 at Donelson: Mantua 16,000; Genoa 11,000; Tobruk 27,000

enter image description here

All meaningful land-facing defense of Donelson was encompassed in the assumption that Fort Henry wouldn't fall; with Henry itself having little in the way of land-facing defense. Although the Union wasn't big on that sort of thing: any Union commander at Fort Henry who didn't promptly capture Fort Donelson would have deserved court martial for cowardice in the face of the enemy.

  • 1
    Given the Confederates' incompetence at establishing forts, no wonder they lost. And if Albert Sidney Johnston "signed off" on them, he was nowhere near as good as some historians (who rank him above Lee except for his early death), think. Also at fault was General Samuel Cooper, whose (honorary) job it was to "inspect forts." (He was an overaged officer who technically outranked both Johnston and Lee.)
    – Tom Au
    Oct 19, 2021 at 13:54
  • @TomAu: Except for Grant and Sherman, the Union wasn't much better. Oct 19, 2021 at 14:08
  • "Grant and Sherman" were enough for the Union to win, given their two to one (or higher) manpower advantage. Even if you consider Lee and (Joseph) Johnston their equal (many historians don't).
    – Tom Au
    Oct 19, 2021 at 14:22
  • Lee is vastly over-rated, just as Macarthur is. Jackson was the best of the Confederate commanders, but even he couldn't find subordinates sufficiently trustworthy to perform and report the most basic reconnaissance. Oct 19, 2021 at 14:25

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service and acknowledge you have read our privacy policy.

Not the answer you're looking for? Browse other questions tagged or ask your own question.