HARRISBURG, JUNE 27. – Carlisle was occupied about ten o’clock this morning by the rebels. At twelve they were three miles this side, and still advancing. Our cavalry force, which has been watching their movements, is generally retiring. The enemy have a line of pickets extending Carlisle to Gettysburg. They are moving in this direction in three columns. What has remained of the Government archives are now being packed up for shipment. The Susquehanna is rapidly rising, which will destroy ail [all] the fords. Gen. Smith, commanding the troops on the other side of the river, considers his position impregnable.