22 
LETTER TO THE SECRETARY OF WAR. 
The main train reached here on the 6th instant, the animals in excellent condition, and the 
men all anxious to press forward to the mountains: the command is a unit, and none are 
desirous to turn back. 
Already are my parties ahead, examining the country between here and the mountains. 
Lieut. Grover, with a select party of seven men, started on the 5th to reconnoitre Cadotte’s 
Pass, and ascertain its practicability for wagons, and open the communication with Captain 
McClellan. 
Mr. Lander, the estimating engineer, with a small picked party, has gone northward to make 
a thorough examination of the Marias Pass, and a reconnaissance of the country to the Kootenaies 
post. This pass is said, in consequence of fallen timber, to be almost impracticable, and is 
here pronounced to be the most difficult of the three passes to be examined. 
Lieut. Mullan, with a small party, has gone to the Flathead camp, on the Muscle Shell river, 
about a hundred miles south of this point, where procuring good Flathead guides, he will go 
through a third pass, and join the expedition at the St. Mary’s village. 
Lieut. Donelson will leave to-day with an advance party of twenty-five men, two wagons, 
&c., making a thorough survey and reconnaissance of the approaches to Cadotte’s Pass, and make 
the road practicable for the wagon train which will follow on the 11th instant, and overtake him 
at the foot of the first dividing ridge. 
I shall, with a small party, start to-day for the Piegan camp at the Cypress mountain, some 
hundred and twenty miles northward, passing along the base of the mountains. I shall make 
an examination of the approaches, and, returning to this point, overtake the train before it 
reaches the St. Mary’s village. 
No apprehensions are felt as to snow: there will be none during the coming month, and the 
first fortnight of the following, except on the mountain peaks. I am determined, if practicable, 
to push my whole wagon train through. On reaching the St. Mary’s village, I shall establish 
a winter post, in charge of Lieut. Mullan, to operate in the passes of the mountains, till driven 
out by snow, and then to explore the lateral valleys and passes, examining the country south¬ 
ward to Fort Hall, to connect the survey with Fremont’s, and northward to the Kootenaies post, 
under the 49th parallel. 
In addition to the reconnaissance of Cadotte’s Pass and opening the communication with Capt. 
McClellan, Lieut. Grover is instructed to return to Fort Benton, make a survey of the Missouri 
river from the Falls to the Milk river, connecting with the survey of that river by Lieut. Donel¬ 
son, and, returning to Fort Benton, get up a dog train and cross the mountains in the month of 
January. The winter post under the charge of Lieut. Mullan, besides furnishing the means of 
obtaining valuable meteorological information, is essential to the success of the dog train of 
Lieut. Grover. 
The labors of the survey up to this point have been of the most satisfactory character, and 
attended with entire success, besides examining a large field of country, and establishing the 
entire practicability of a railroad. The Missouri river is believed to be navigable at all seasons 
of the year, except when obstructed by ice, to the Falls of the Missouri, for steamboats not 
drawing over eighteen inches of water. Slight obstructions may occur which can be removed 
at a comparatively small expense. The survey of the Missouri river from the Falls to a small 
distance below Milk river, where Lieut. Donelson’s labors terminated, will be taken up next 
month by Lieut. Grover, and continued. On their joint labors and collections a reliable report 
on its navigability will be based. 
I have the honor to be, very respectfully, your obedient servant, 
ISAAC I. STEVENS, 
Governor of Washington Territory, in Charge of Exploration. 
Hon. Jefferson Davis, 
Secretary of War. 
