Custer embarked on his expedition with 1000-1200 men, in 110 wagons with numerous horses and cattle of the 7th Cavalry, along with artillery and two months food supply.

En route to the Black Hills, Custer's party managed to locate the track of Hardy's group when they spotted two lines of sunflowers that had grown along the ruts of his passing wagons.

By August 2, 1874, this force had reached a point eight and a half miles south-east of the mountain,[7] to a location they named Agnes Park,[8] having had a number of peaceful encounters with Native American settlements.

The first discovery goes uncredited, however an undated diary entry by William McKay, a miner accompanying the expedition, notes that while camping at the newly named Custer Park, "In the evening I took a pan, pick and shovel, and went out prospecting.

"[10] A significant discovery was made on August 1 when tests of the soil by the French Creek determined that a miner could earn as much as $150 per day mining in the Black Hills.

As this subject has received the special attention of experts who accompanied the expedition, and will be reported upon in detail, I will only mention the fact that iron and plumbago have been found and beds of gypsum of apparently inexhaustible extent.