<p>Stamp of the German Empire - plebiscite area "Allenstein", definitive stamp, Reichspostamt-issue (war press with flags) from 1914/15 with three-lines, black ovewrprint in Latin capital letters "PLÉBISCITE / OLSZTYN / ALLENSTEIN"<br><b>Stamp</b>: Michel No. 11a (= Michel No. 113 (Reichspostamt Berlin with flags)); Yvert &amp; Tellier: No. 11 (DR-AL 11); AFA: No. 11 (DR-AL)<br><b>Color</b>: dark yellowish green<br><b>Nominal value</b>: 1,25 Mark<br><b>Watermark</b>: Germany No. 1 (rhombs)<br></p>
<b>Postage validity</b>: from 3 April 1920 until 20 August 1920 <div style="display: none;">date QS:P,+1920-00-00T00:00:00Z/9,P580,+1920-04-03T00:00:00Z/11,P582,+1920-08-20T00:00:00Z/11</div><br><b>Postmark</b>: Krupinnen, <time class="dtstart" datetime="1920-04-29" lang="en" dir="ltr" style="white-space:nowrap">29 April 1920</time><i>(Krupinnen (then: East Prussia - Regierungsbezirk Gumbinnen - Landkreis Treuburg); contemporary: <a href="https://de.wikipedia.org/wiki/Krupin_(Wieliczki)" class="extiw" title="de:Krupin (Wieliczki)">Krupin</a> in Poland)</i>
Deutsche Reichspost - "Commission d'administration et de plébiscite Olsztyn - Allenstein"
scan of original