WASHINGTON, D. C., July 26, 1864.

General L. THOMAS:

The Secretary of War and General Grant both disapprove the raising of any more cavalry regiments. If General Burbridge levies horses in Kentucky they should be used for the cavalry we now have.

H. W. HALLECK,

Major-General and Chief of Staff.

(Copy to General S. G. Burbridge.)

WAR DEPT., PROVOST-MARSHAL-GENERAL'S OFFICE,

Washington, D. C., July 26, 1864.

Honorable EDWIN M. STANTON,

Secretary of War:

SIR: Upon the letter of Major General C. W. Sandford, New York militia, dated July 25, referred to me for report, I have the honor to report as follows:

On the 21st of April last the Governors of five Western States offered to the President "infantry troops for 100 days" service" upon certain stipulated conditions, one of which was that the men in their service should not be exempt from draft, but if drafted should be credited with the length of time they had been in the 100-days" service. The legality of this stipulation was passed upon by the Solicitor of the War Department May 9, 1864. He says:

The acts of Congress alone prescribe who shall and who shall not be drafted. No agreement between the President and the Governors would be lawful if made in violation of these acts. The sixth section of the accepted proposition of the Governors is in conformity with the law and requires the troops mustered for 100 days to continue liable to draft. Although these troops are in the special service of the United States, they are not in that service in any sense contemplated by the acts of Congress which provide for exemption from draft.

The conditions under which these troops were accepted are the same in substance as those which governed in a like case last year. They were printed and circulated and have been generally applied to other 100-days" troops called for since their adoption from other States besides the five specified.

On the 5th of July the President made a call on the Governor of New York for 12,000 militia for service not to exceed 100 days. In communicating his call be telegraph you requested the Governor to send the troops immediately to Washington, and explained the necessity for his doing so. Nothing was said in the dispatch as to the conditions under which the troops were to be accepted, but it was the intention to apply the same rules to them as the others.

On the - of July, and without the knowledge or approval of this department, Major-General Sandford published an order in New York quoting the law and announcing that the 100-days" men would be "exempt from the draft made in September next." On the 19th of July the Governor of New York telegraphed to me asking whether the 100-days" men would be exempt from any draft which might take place while they were in service. I communicated to him the same day your decision that it was the understanding of the Department that they would be governed by the rules applied to the same character of troops from other States, and inclosed him a copy of those rules.