From Capt. McClure's Company.

Camp Cumberland Gap, Tenn.,
June 20, 1862.

Mr. Editor: -- The Federal troops occupy Cumberland Gap. The National Flag is planted on its highest pinnacles, on its strongest batteries. It was the honor of the 16th Ohio to perform what might be denominated the ceremony of occupation. Salutes were fired, acclaiming cheers given. The evacuation was so complete, the destruction of property so circumstantial, as to remove all troubles of victory save the strong position intrenched by the most stupendous labor. The vast spoliation of commissary stores asserted good living on the part of the Confederates. Barrels of flour, bacon, beans, rice and all the multiplied elements of subsistence were profusely destroyed. Hundreds of tents left standing were riddled by the long dirks of uncouth manufactory, which depend in a buccaneer-like manner from the girths of all rebels, and which they, no doubt, thought would be brandished over many a fallen foe, and materially aid in repelling the bacon-fed hirelings of Northern aggression from the sacred soil of the Southern Confederacy. Erected on the most commanding localities on either side of the Gap were embankments for 8 batteries, which completely swept all the avenues of accessability in front, on the flanks, and in the rear of this great natural stronghold. Fifty thousand men would have been cut to pieces had they attempted to assault Cumberland Gap by the road leading through it. They must have breasted for over four miles the converging fire of 35 pieces of artillery. Rifle pits environed the mountains on every side. Driven from one, the Confederate troops could have fallen back into a second line of defenses more impregnable than the first. The assailing foe exalting over the dislodgment of the enemy from his fortifications would suddenly have found himself exposed at a deadly range to all kinds of embanked cross fires. It may safely be said that Cumberland Gap, fortified as it is, approaches impregnability. Possessed by a braver people, moved by a holier purpose, it would have defied all its enemies. Whether it justifies the designation of the "Gibralter of America," with which Gen. Morgan had baptized it, I am not prepared to say. The general opinion of army officers, however, concurs in awarding it great military strength.

It now becomes my pleasure to relate the combinations and movements which possessed Cumberland Gap without the shedding of blood or the firing of a single gun. This achievement reflects great credit on the capacity of Gen. Morgan. The main pillar of Generalship is the accomplishment of an antagonized purpose with the least possible effusion of blood, with the least possible exhaustion of men, combined with the greatest possible economy of time. The expulsion of the Confederate troops from Cumberland Gap by a purely strategical movement is an event worth of commemoration. On the 7th day of June the 7th division of the army of Ohio broke up its encampment at Cumberland Ford, taking the road leading across Cumberland mountains by Roger's Gap into Powell's Valley, Tennessee. Carter's Spear's, and Baird's brigades advanced by a more circuitous route through Big Creek Gap. A Gap in popular estimation would signify a complete separation of the mountains through which transportation would be easy. The points designated were not what in popular estimation would be Gaps, but merely slight indentures in the mountain's side, and sometimes over its highest peaks. Roger's Gap is 19, and Big Creek 34 miles from Cumberland Gap. The roads leading over these Gaps were more bridle paths, both of which had been industriously blockaded by rebel sagacity. The idea of an army, with its heavy liege guns, with its miles of subsistence trains, with all the multifarious trappings of war, crossing such a precipitous mountain path had never entered the mind of the Confederates. On the 11th of June the 26th brigade effected a landing in Powell's Valley. On the 16th, Carter's Spear's and Baird's brigades formed a junction with the 26th. Thus, by most stupendous labor, the 7th division executed a flank movement on Cumberland Gap. The point of junction of the division was 40 miles west of Cumberland Gap. The assumption of this position imperilled the communication of Cumberland Gap and endangered Knoxville itself. The rebels were thunder struck amazed, nonplused. They must either be bagged in the Gap, flight us in the open field, or evacuate immediately. Rebel wisdom adopted the last. On the 18th we commenced our advance, expecting to encounter a force of the enemy entrenched about ten miles from Cumberland Gap. We continued our march and about 6 o'clock P.M. the 16th Ohio entered the enemy's entrenchments and had the first salute fired in honor of victory. The last rebel had left about two hours before our advance guard arrived.

It has been asserted by some writer on military science that the policy regulations of an army evidence the quantity of discipline attained. If this theory is correct the Confederate troops at Cumberland Gap were cursed with a prodigal deficiency of discipline. A more dirty, filthy, vermin-infected place than Cumberland Gap cannot be instanced. From collected accounts the rebels of this vicinity were a dirty, ill-clothed, ill-couraged, tripe-visaged agglomeration of long-haired bushwhackers, which would be a slander to military science to denominated organized army. Last accounts avowed this aggregation of scoundrels to be on the threshold of disorganization. Appearances foretell that they will congregate at Moorestown to make a stand for the defense of the Virginia & Tennessee Railroad. I am not prepared to say when we will advance. I think, however, that inside of two weeks we will turn our backs on Cumberland Gap and our faces southward to Knoxville. One more stroke will reclaim Tennessee throughout its entire limits to the dominion of the Federal Government.

A.S.M.