In WWI, Lydavėnai (later Lyduvėnai, russ. Lidovjany) was passed through by Bavarian cavalry the following day after the German push into Žemaitija began on April 27, 1915. The cavalrymen were from the reco Abteilung Gonnermann of the Bayerische Kavallerie-Division which was speeding to flank Šiauliai from the south. During the German occupation Lydavėnai acquired some importance when a strategic railway line was built in 1915 – 1916 from Tilsit (East Prussia) via Tauragė to Šiauliai. Lydavėnai had no post office in czarist times, and no such facility was set up during the German occupation, the nearest Postgebiet Ob.-Ost branch being at Kielmy / Skaudwile.
When the German army retreated from Russia at the end of 1918 and the Red Army advanced through northern Lithuania and Šiauliai in the first half of 1919, the southern part of the vital railwail line Tilsit – Šiauliai was not abandoned and was kept being guarded by volunteer Detachement Randow within Generalkommando 52. For the rest of 1919, this rail line, including Lydavėnai, acquired considerable military importance as a supply route to German units in Latvia and northern Lithuania, and continued being supervised by German border guards (Grenzschutz). In the second half of 1919 the railway line, including Lydavėnai, was under the control of the bermontininkai (so-called Russo-German Westarmee), whose postal needs were served by the volunteer Feldpost 3072 in Šiauliai.
A mandate to set up as įgaliotinis, as from March 18, 1919, a Lithuanian postal facility at Lydavėnai railway station was given to Pranas Šimkus from the Raseiniai P.O. The status of the facility is not certain but it served as a postal transfer point between mail-carrying trains and the local postal facilities. The first such mail exchange took place on June 25. In early January 1920 Pranas Šimkus was transferred to Tauragė and replaced by Dobrovolskis who in turn on May 12 went to Raseiniai.P.O. The new įgaliotinis at Lydavėnai came to be Petras Gudmonas who on October 16, 1920 was replaced by Adolfas Danilevičius from Tauragė P.O.
On June 1, 1937 an additional agentūra was opened in the adjacent township now spelled LydUvėnai which maintained a close contact with the agentūra at the railway station of the same name. Though administrative details are not known they point to the agentūra at the railway station eventually becoming just an exchange point. As the postmaster of the agentūra in the Lyduvėnai township was appointed Antanas Gedminas.
The earliest stamps known from LydAvėnai were values of Fourth Berlin Issue, followed by the Sėjėjas Issue etc. As at first LydAvėnai had no formal postmarker, cancelling was done by manuscript.
A standard canceller inscribed “LYDAVĖNAI” was provided ca.1920. In ca.1937 another canceller inscribed “LYDUVĖNAI” was put into use, probably coinciding with the gradual transfer of the R/S agentūra to the agentūra in the township.
In the absence of a formal registration cachet, early registration marking was done in MS by forming a box with “R” and serial number.
Known provisional cancelling by MS:
18 / X / 19 single, Berlin IV 60 [colln. V. Jurkša]
Registration by MS box:
118 16 – XI – 1919 reg. cover to Germany, Berlin IV 10, 30, 60, 1a [colln. V.Jurkša]