Estonia German Occupation 1916-17 , Tartu Overprint Stamp .

Here is a interesting stamp found in a worldwide collection recently.At first I thought the purple overprint of TARTU was a cancel of the second largest city in Estonia . But I found nothing to say this is a postal cancel ,so more information is needed.
After the collapse of the Russian Empire of the western area .The city of Tartu became the northern reachs of the German Occupation of 1916-17.This stamp with the black overprint is listed in the Scott catalog under Lithuania,with a footnote that it was used in five former provinces of the Russian Empire with ESTLAND being the furthes North ,but why the extra overprint ?

Fantasy/bogus overprint? Part of a fiscal/postal/telegraphic cancellation?

Is the stamp still gummed?

There seems to be more about these "Ob Ost " stamps on the Estonian Philatelist website .Sounds like the German Army after entering Estland{Tartu being the main city} decided to overprint some Russian stamps with German values .The head postal authority in Lithuania which handled the out going mail for the Baltic region was not happy to see Russian stamps and told those in Tartu to stop using them for out going mail ,and shipped up the OVERPRINTED Germania stamps .But up there ,he let them still do local stuff in TARTU ,now im guessing this is a local issue created by the post master. ---just a guess .

I'm not 100% sure on the exact details of their usage, but I think they're a provisional usage of the earlier Ober Ost issues during the closing days of WWI. Here are a couple on cover:

Nice covers PostmasterGS. :)

So basically the "Tartu" marking is indeed a postal cancellation from Tartu/Dorpat.

PostmasterGS, are there any manuscript dates or arrival CDS postmarks on the reverse of these two items?

Those aren't actually mine. I pulled those images from a Google search.

POSTMASTER GS-----Thanks for those scans and now I need to write up a explanation for my album.

floortrader,

I went back and looked at the sites where I found those photos, and one of the covers had a receipt guaranteeing delivery by 23 November 1918. That would be after the Germans turned over authority to the Estonian Provisional Government (16 November 1918). So these likely were provisional issues used in the brief period after German occupation, but before the first Estonian issue (22 November 1918).

Gibbons note after s.g. 4

The word TARTU sometimes found handstamped on this issue is a postmark,

Okka

If you search thru E-BAY today there are four or five different cities that used a similar postal cancel,so with so many available in just this week ,it must of been used for a while,I will footnote it on a album page as a period cancel,thanks everybody.

here is a small article about Estonian provisional cancels:

http://www.efur.se/articles/provcanc.html