"SIR: It becomes my painful duty to inform you of the assassination of the greater part of Lieutenant Colonel Harney's detachment, by the Indians, on the morning of the 23d instant, on the Coloosahatchee River, where they had gone, in accordance with the treaty at Fort King, to establish a trading-house. The party consisted of about twenty-eight men, armed with Colt's rifles; they were encamped on the river, _but unprotected by defenses of any kind_, and, it is said, without sentinels. The Indians, in large force, made the attack before the dawn of day, and before reveillé; and it is supposed that thirteen of the men were killed, among whom were Major Dalham and Mr. Morgan, sutlers. The remainder, with Colonel Harney, escaped, several of them severely wounded. It was a complete surprise. The Commanding General, therefore, directs that you instantly take measures to place the defenses at Fort Mellon in the most complete state of repair, and be ready at all times to repel attack, should one be made. No portion of your command will, in future, be suffered to leave the garrison except under a strong escort. The detachment will be immediately withdrawn. Should Fort Mellon prove unhealthy, and the surgeon recommend its abandonment, you are authorized to transfer the garrison, and reinforce some of the neighboring posts. "I am, Sir, GEO. H. GRIFFIN, _Assistant Adjutant General_. Lieutenant W. K. HANSON, Commanding at Fort Mellon." The Indians killed ten men belonging to the military service, and eight citizens, employed by the sutlers; while Colonel Harney and fourteen others escaped. The Indians obtained fourteen rifles, six carbines, some three or four kegs of powder, and about three thousand dollars worth of goods. Lieutenant Hanson, commanding at Fort Mellon, on receiving the order which we have quoted, seized some thirty Indians at that time visiting Fort Mellon, and sent them immediately to Charleston, South Carolina; whence they were embarked for the Indian Country, west of Arkansas, where they joined their brethren, who still resided upon the Cherokee Territory. In these transactions, the Exiles who remained in Florida appear to have taken no part, at least so far as we are informed. They labored to obtain the treaty of peace; but such was the treachery with which they had been treated, that they would not subject themselves to the power of the white people, and were not of course present at the treaty; nor were they recognized by General McComb as a party to the treaty, or in any way interested in its provisions. Indeed, we are led to believe that General McComb adopted the policy on which General Taylor usually practiced, of recognizing no distinctions among prisoners or enemies.