headquarters detachment Sixteenth and Seventeenth army corps, on board steamer Clara Bell, Grand Ecore, La., April 5, 1864.expedition after Harrison's guerrillas. Brigadier-General A. J. Smith, commanding detachment of the Sixteenth and Seventeenth army corps, reached this celebrated point on Sunday afternoon, Admiral Porter's fleet of ironclads having preceded our transports up this crooked river. Major-General Banks and staff arrived here at sundown Sunday, on his flagship Black Hawk. Our gunboats met with no opposition on the trip up the river. A gang of rebels fired from the steep banks of the river upon a small steam-tug without injuring any one on board. Natchitoches, one of the oldest and most picturesque towns in this State, which is six miles from Grand Ecore by land, was occupied by the advance of General Lee's cavalry force, without any molestation from the enemy on Saturday. Our colors now float from the town-house, and the inhabitants appear to be perfectly reconciled to the sudden entree of the “Yankee horde” into their peaceful but sadly impoverished town, and thus far no insults have been offered our troops, who seem to reciprocate this respect by behaving with the utmost decorum. The ladies have been known to look upon some of our gallant soldiers as they passed beneath their balconies without a frown, which indicates a hopeful state of feeling, for generally the feminine gender in this section of the socalled Confederacy are most virulent rebels, and they never allow an opportunity to pass without hurling bitter invectives against the Northern people and their abominable institutions. The exceedingly low water in Red River this season, has operated most seriously against our projected movements, causing a postponement of the victories which are sure to greet our forces in this department as soon as the advance on Shreveport begins. At present we are at a standstill, several transports and gunboats having got aground on the way up from Alexandria. Admiral Porter feels quite confident a sufficient rise will take place within three or four days to admit of the passage of all our transports and the iron-clad fleet. In crossing the falls at Alexandria, the Eastport, one of our most valuable and formidable iron rams, ran aground on the shoals, and for thirty hours her condition caused the most serious apprehensions, all attempts to haul the grim monster off by means of hawsers proving ineffectual. The efforts of several tugs and transports finally released her from her perilous position without any serious injury. expedition to Campti. At half-past 8 o'clock Monday morning, General A. Smith ordered Colonel Gooding, commanding the Sixth Massachusetts cavalry, to proceed with the following troops upon a reconnoissance to the town of Campti, six miles distant, for the purpose of capturing or dislodging a band of Harrison's guerrillas, numbering some three hundred men: Three hundred of the Second New-York cavalry, two hundred from the Third Rhode Island, and one hundred men from the Eighteenth New-York cavalry, together with two regiments of infantry under command of Colonel Hubbard of the Fifth Minnesota, comprising the Thirty-fifth Iowa, Lieutenant Keeler, and the Fifth Minnesota volunteers. As our cavalry scouts advanced within a mile of the town, the rebels, who were concealed behind trees and bushes, opened a fearful and deadly fire upon them, causing many a brave fellow to writhe in the dust. Our skirmishers were at once dismounted and deployed, with the expectation of flanking the enemy. As fast as our men advanced, however, the chivalrous foe retreated, endeavoring to draw our men toward the town. Finding it impossible to get within carbine-range, Colonel Gooding ordered a charge in the direction of a small bridge spanning a bayou, where the rebels appeared to be making a stand. At the word of command, our cavalry dashed bravely on to the foe; but, sad to relate, an unforeseen misfortune thwarted all their heroic attempts to dislodge the enemy. Arriving at the bridge, our squadrons were suddenly halted in considerable disorder by discovering that several planks had been removed from the flooring of the bridge. The enemy, during the confusion, took advantage of our dilemma and poured a heavy volley into our men from their hidingplaces on the opposite bank of the bayou. It was at this point that Adjutant Dunn, while gallantly leading on his men, fell mortally wounded, a bullet piercing his head, Few lives have fallen at the hands of the merciless foe during this war that will be more universally lamented than warm, noble, generous-hearted Adjutant Dunn, the pride of his regiment. Colonel Gooding at once deployed his infantry and cavalry, and was in the act of flanking the town, experiencing great difficulty in crossing the bayou, when, unfortunately, the gunboats approached, and, hearing the firing, they opened upon the town with one or two of their heaviest guns. Several shells burst in close proximity to our advance, and Colonel Gooding, after endeavoring to signal the boats by waving his handkerchief, failed to attract the attention of the officers of the fleet. Major Davis, of the Third Rhode Island cavalry, was sent on board to notify the gunboats of the mischief. The rebels embraced the opportunity to retreat, and thus all our efforts to capture them were foiled. Our loss was much heavier than that of the enemy, the cavalry sustaining the entire loss in killed and wounded. I am indebted to Surgeon A. T. Bartlett, of the Thirty-third Missouri volunteers, for the following list of casualties. The wounded are now being placed on board the steamer Jennie Rogers, preparatory to their removal to Alexandria, where suitable hospitals have been established for the reception of sick and wounded troops. Our loss was ten killed and eighteen wounded.