In WWI, Gruzdžiai (Gruzdzi, Grusdi, Grusen), a township ca. 20 km north of Šiauliai (Schaulen), was involved in the swift German advance resulting in the taking of Šiauliai on April 30, 1915, then their retreat and their repeated taking of Šiauliai on July 21. Around Gruzdžiai, the troops active on both sides were mostly cavalry, with German 3. Kavallerie-Division to start with.
When the German army retreated from Russia at the end of 1918, units of the Red Army appeared in Gruzdžiai in January 1919. During the German Grenzschutz drive on Riga they were pushed out on March 10, 1919 by cavalry units of Detachement Schlenther. A number of local Lithuanian self-government bodies were formed in the area, though in the second half of 1919 tensions developed with the “bermontininkai” who foraged the countryside for daily necessities.
A mandate to establish a Lithuanian post office in Gruzdžiai was given, as from May 1, 1919, to Adomas Lisauskas from the Šiauliai P.O. However, it seems that some postal services had already been available there prior to this formal appointment (or confirmation ?).
For stamps, Gruzdžiai had the benefit of the early stock still held at Šiauliai, which included values of the Vilnius Issues. Among other early stamps available at Gruzdžiai seem to have been Second Kaunas and Second Berlin Issues, soon followed by the ubiquitous Fourth Berlin Issue.
With no standard Lithuanian postmarker, earliest cancelling in Gruzdžiai was done by handwriting, indicating date and place.
Towards the end of 1919 Gruzdžiai was using a box-type cachet which was not quite the standard cachet for registration or for money orders, so it may have been home-made. It also stands out by the spelling of the post office’s name as “GruŽdžiai”.
A standard calendar-type postmarker seems to have been supplied in 1920, but a home-made registration cachet was used as late as 1921.
Known provisional cancellations:
Cancelling in MS date and place:
17 / IV  single, Vilnius I 10 [colln. Brazdeikis]
24 / IV  single, Kaunas II 30 [colln. ?]
23. V. 19 cover to Germany, Berlin II 50 [colln. Bubnys]
19 / VIII.19 cover to Germany, Berlin IV 60 [colln. ?]
Box-type cachet inscribed “Gruždžiai”:
21 X 19 letter to Kuršėnai, Berlin IV 15 x2 [colln. Bubnys]
10. 11. 19 reg. letter No. 245 to Bauske, Latvia, Berlin IV incomplete set [colln. Lapas]
Home-made registration cachet with spelling “Gruzdžiai”
1153 21. XI. 1921 reg. cover to USA, Sėjėjas 2a x2 [colln. Doniela]