Then why was this forlorn hope inaugurated?
What credit could any one expect to obtain by bucking for miles up the deep, dangerous gorge filled with difficult rapids, which Powell had found hazardous and well-nigh impossible, coming down with the current?
The leader of this superfluous endeavour was Lieutenant Wheeler, of the Topographical Engineers, who had been roaming the Western country for several years with a large escort.
For some reason, Wheeler seems to have been disinclined to give Powell credit for his masterly achievement.

On the map published in his Report, under the date 1879, TEN YEARS AFTER POWELL'S TRIUMPH, he omits his name entirely, and he also fails to give Ives credit on the river, though he records his land trail.

In the text I fail to find any mention of Powell in the regular order, and only towards the end of the volume under a different heading.

As the book gives an admirable and detailed review of explorations in the West, one is completely at a loss to understand the omission of credit to two of the most distinguished explorers of all.
Wheeler accepted White's story because one of his men who knew White at Camp Mohave, "corroborated" it.

How could a man who knew nothing about the canyons give testimony worth consideration, for or against?
Wheeler had also been informed by O.D.Gass, who, with three others, had worked his way up the Grand Canyon some few miles in 1864, that in his opinion it was impossible to go farther than he had gone.