Richd. C. Drum to George L. Andrews, July 16, 1861

Lieut. Col. GEORGE ANDREWS, Commanding Fort Yuma, Cal.:

SIR: The security of your command and the position it now occupies is of vital importance, and requires, the general commanding believes, the most watchful care on your part. It is therefore desirable that you should make such necessary preparations for the defense of your post as the means at your disposal will permit. To enable you the more certainly to procure valuable and reliable information of any hostile operations in the south or west, and to receive timely notice of the advance of any force in the direction of your post, the general desires you to make such arrangements with the tribes of friendly Indians and others favorably disposed toward our Government, as well as keep you constantly advised of the movements of armed parties in the directions indicated. The general also wishes you to keep him advised of any movements having for their object either the invasion or seizing upon of any part of the States of the Republic of Mexico on this coast. You are expected to forward all reliable information you may recelve for the information of the general commanding.

Very respectfully, your obedient servant,