Confederacy, (Trans-Mississippi) 1863, 10¢ Blue, Horizontal Strip of 4. Four mostly large margins (close at top left), fresh bright color, tied by three strikes of blue "Petersburg, Va./Oct. 26" (1863) cds on cover to "Capt. F. P. Leavenworth" in Shreveport, La. with manuscript endorsement "Via Meridian, Miss.", cover colorless embossed corner card of "Collegiate Seminary for Young Ladies, Petersburg, Virginia/Rev. A.J. Leavenworth, Principal" (Dietz Type I) at top left, interesting pen & ink doodling on reverse by recipient, flap torn away, Extremely Fine, Illustrated in the Trepel/Walske book Special Mail Routes of the American Civil War: A Guide to Across-the?Lines Postal History and featured in Jan. - March 2007 issue of the Confederate Philatelist (Pictured in Monroe Book, pg. 59); with 2006 C.S.A. certificate. Scott No. 11  Estimate $7,500 - 10,000. ONE OF THE FINEST TRANS-MISSISSIPPI EXPRESS COVERS EXTANT. THE EARLIEST USE OF THE GOVERNMENT EXPRESS, WHICH COMMENCED IN OCTOBER 1863.This extraordinary Trans-Mississippi Express Mail cover surfaced in 2006 and is one of two known express covers with a college imprint. Because of the blue Petersburg, Virginia, October 26 (1863) postmark, this cover is now the earliest known Trans-Mississippi Express Mail cover. The previous earliest known Trans-Mississippi usage was October 30, 1863. The evidence supporting the crucial year date of 1863 is the fact that the blue Petersburg, Virginia, cancellation was last used on September 1, 1864, which therefore dates this cover as 1863 (CSA Authentication Service Certificate issued). The envelope was addressed to Captain F. P. Leavenworth (Frederick Peabody Leavenworth) and was sent by Reverend Abner Johnson Leavenworth, father of Captain Leavenworth and Principal of the Collegiate Seminary for Young Ladies. Frederick Peabody Leavenworth was commissioned as a Captain in early 1862, and served as Ordnance Officer under General E. Kirby Smith in the Trans-Mississippi Department. Captain Leavenworth survived the war and died in 1920. $0 (Image)