The Confederates did not attack through the tunnel. Because of the fold in the terrain and angle of attack and the fact that the Federals were on their bellies at the time they thought the Confederates attacked through the tunnel. It would have been absolutely impossible for any of the 5th Iowa to see the mouth of the tunnel.
I am intimately familiar with the fight at Tunnel Hill, walked what is left of the terrain, lead several historical walking tours with the Chief Historian of the Chickamauga- Chattanooga NMP and we remain unconvinced that did not take place.
Please let me know if you have any questions.
Gerald D. Hodge, Jr.
War Between the States Historian
Historian: 39th Georgia Volunteer Infantry Regiment