HEADQUARTERS THIRD BRIGADE,
August 14, 1863.

CAPTAIN: In reply to circular of the 12th instant, from headquarters Army of the Potomac, I have the honor to submit the following report supplementary to that of the battle of Gettysburg: June 28. -In camp near Frederick City.

June 29. -Left camp in the morning, and marched 2 miles beyond Liberty, in the direction of Johnsville. Camped at 7 a. m. [p. m.] June 30. -Left camp at 4 a. m., arriving at Union Mills about 4 p. m., when we bivouacked for the night.

July 1. -Broke camp at 6 a. m., arriving at Hanover about 3 p. m. Left again at 5 [p. m.], and arrived within 3 miles of Gettysburg at 1 a. m.

[July 2], when we bivouacked.

July 2. -Started at 4 a. m. ; went about 2 miles, when we got into position; remained some 2 hours; then crossed the creek, and lay in position awaiting orders until about 4 p. m., when we were ordered to the front; immediately on arriving there became engaged; held that position, and bivouacked on the field that night. (See previous report.)

July 3. -Remained on the field of the previous days fight until about 9 a. m., when we were relieved by the First Brigade and Ninth Massachusetts, of the Second Brigade, we taking their old position farther to the right.

July 4. -Same position of previous day until we were ordered to relieve General Bartletts brigade, of the Second [Sixth?] Corps. July 5. - Same position as previous day. Started about 5 p. m. in direction of Emmitsburg. Bivouacked on the road about 10 p. m.

July 6. -Started at 6 a. m., and arrived at 12 m. within 3 miles of Emmitsburg, when we camped.

July 7. -Left camp about 6 a. m., and arrived within 5 miles of Frederick City at 6 p. m., when we bivouacked.

July 8. -Broke camp early in the morning, and arrived at Middletown about 4 p. m.

July 9. -Left Middletown early in the morning, and arrived within 2 miles of Boonsborough about noon.

July 10. -Broke camp early in the morning, and arrived at Jones Cross-Roads about 3 p. m. The Eighty-third Pennsylvania went on picket immediately.

July 11. -Changed direction of the line to the right early in the morning. In the afternoon advanced to Pleasant Valley.

July 12. -Changed front to the left, and advanced on the Hagerstown and Sharpsburg pike.

July 13. -Camped in front of pike; two companies of the Eighty-third Pennsylvania on picket.

July 14. -Advanced to within 1 mile of Williamsport.

July 15. -Left camp at 4 a. m., and arrived near Burkittsville at 5 p. m., where we bivouacked for the night.

July 16. -Left camp about 4 a. m., and arrived near Berlin 12 m., and went into camp.

July 17. -In same position until about 3 p. m., when we recrossed the Potomac and camped near Lovettsville.

July 18. -Broke camp at 4 a. m. ; proceeded 7 miles in the direction of Purcellville; bivouacked at 12 m.

July 19. -Left camp at 8 a. m. ; marched 4 miles to Purcellville.