Prussian postal stationery envelope 2 sgr. blue with additional franking 1st issue 1 sgr. on rose with clear to full margins, endorsed "Militairbrief der Bundesfestung Luxembourg" addressed to an instrument dealer at Mark-Neukirchen in Saxony, the stamp cancelled with clear numeral "1520" with adjacent "TRIER 24 4"; seal on reverse cut out, otherwise fine. A very rare letter; we have no further Prussian postal stationery recorded with a 1st issue franking
