In November 1861, Gen. Felix Zollicoffer sent Capt. Thomas Estill and Capt. Victor Von Sheliha along the Cumberland River to find a practical base camp, and Mill Springs was chosen because of its natural terrain, abundant food and forage, a grist mill, saw mill, and a ferry. To build earthworks for the Confederate base, 500 axes, 300 shovels, 200 picks, and other entrenching tools were requisitioned from Nashville. Less than a month later, as fortifications on both sides of the river neared completion, Zollicoffer moved most of his forces to Beech Grove on the north bank, a poor tactical decision because the river blocked the Confederate line of retreat. Even so, he remained optimistic and ordered a second set of earthworks built under Estill and Sheliha. These fortifications at Beech Grove were skillfully designed and formidable, running across the peninsula along a ridge as a broken line of breastworks with redans on the east and west ends and in the center, another redan on the road to protect the route to the ferry landing, a fourth gun emplacement southwest of the main line above White Oak Creek, and a final line protecting the flanks. A New York Herald reporter soon dubbed the enclosed camp and earthworks "Zollie's Den." The works were never tested. After the Battle of Mill Springs, Confederate troops fell back to these river fortifications, but within hours crossed to the south side of the river and continued retreating to Tennessee. When Union forces attacked the next morning, Zollie's Den was deserted, and the Confederates had left behind 14 cannon, 200 wagons, 2,000 horses and mules, and all their food supplies.