Kazlų Rūda is a township and a railway junction ca. 35 km south-west of Kaunas. In World War One, Kazlų Rūda was taken by German infantry during their preparations to storm the fortress of Kaunas, which fell on August 18, 1915. Kazlų Rūda was the rail section where, starting on August 7, the assault on the Kaunas fortress was directed from a Command Train by the commander of German Tenth Army, Gen.von Eichhorn, and his operations staff.

After the German retreat from Russia at the end of 1918, Kazlų Rūda’s rail junction was guarded by German border guards (Grenzschutz). During the Red Army’s planned break-through towards East Prussia in February 1919, some of the Kazlų Rūda rail installations were blown up by Bolshevik activists on February 14, but the overall advance was foiled at Kėdainiai and Alytus.

In czarist times, Kazlų Rūda had had a post office (Kozlova-Ruda) but none during the German occupation. A Lithuanian postal facility was set up, possibly at the initiative of a municipal body, on or about September 1, 1920 (according to Ričardas Vainora), but there is no evidence of an early formal appointment of a postmaster.

For stamps, Kazlų Rūda had Fourth Berlin Issue and, perhaps exceptionally, some First Berlin values (this needs checking), followed by the Sėjėjas Issue etc.

Having no postmarker, for cancelling a provisional cachet was used. As far as reconstruction permits, it consisted of possibly four lines: the first for place-name, the second for a date, and the third seems to have read “PAŠTO”. The entire cachet probably read “[Kazlų] Rūdos [date] [PAŠ]TO [agentūra]” or the like.

The second known type of provisional cancellation consists of a single-liner cachet probabaly reading “Kazlų Ruda”. Again, so far only a fragment has come to light.

The third known cancellation cachet is a single-liner KAZLŲ-RŪDA, of which so far only a large fragment is known. The use of capital letters suggests that it was used at the busy Kazlų Rūda railway station to pay for the dispatching of telegrams. If so, the place name would have been preceded by an abbreviation such as ST, St, st. or the like.

By mid-1922, a standard calendar-type postmarker was provided.

Known provisional markings:

Cancelling by a three-liner cachet:
[...19] 21 single, Berlin I(?) 30 [colln. Liesis]

Cancelling by a single-liner cachet:
no date single, Berlin IV 30 [colln. V. Jurkša]

Cancelled by place-name in capital letters:
no date single, S?j?jas 1a [colln. V. Jurkša]