A possible developed timeline of the World War II events described in the four Subject Zero audio files.
75,0000.B.C.E.= As part of the early stages of developing the second salvation solution members of the First Civilisation tried to create a more powerful version of a shard as a principle enlargement proof of concept but while they were successful with the prototype being able to protect an area the equivalent of a medium multistorey building as a principles enlargement proof of concept but like the larger city and global shard shield concepts they didn't have the time or resources for sufficient mass production so it was forgotten.
1940 The Nazis discover the boosted Shard in either Germany or it's occupied territory and was eventually sent to the Cologne Gestapo.H.Q., (ELDE Haus) for safe study and storage it protects the building from receiving all but minor bomb damage while 90% of the city is flattened.
Sometime between 1940 and 28th September 1944= Ehrenfeld Gruppe teenage member Bartholomaus, "Barthel" Schink infiltrates the s Cologne Gestapo.H.Q., (ELDE Haus) to gather intelligence to plan future disruption activities but also to steal the Shard for his Assassin ally Oskar. The theft is suppressed by the Gestapo, (to keep the Shard's existence a secret and prevent a loss of face). Barthel Schink then hides it in one of the spires of the, "Hihe Domkirche St.Petrus", (High Cathedral of St.Peter) unwittingly enabling it to remain standing after being hit 14 times by Allied bombers and informs Oskar of it's location.
29th September 1944= Hans Steinbruck and Roland Lorent attempt to steal explosives for a planned attack on the ELDE Haus but are foiled by a guard.
8th-15th October 1944= 63 Ehrenfelder Gruppe members were arrested by the Gestapo for their insurgent activities including the former Edelweiss Pirates Navajo subgroup member Mariam Kurtz and then later Barthel Schink and are held prisoner in the ELDE Haus Cell 7. They are interrogated not only about the Ehrenfelder Gruppe's insurgent activities but also the location of the stolen Shard but neither cooperate.
25th October 1944= Heinrich Himmler ordered a crackdown on the Edelweiss Pirates and other related internal insurgency groups.
10th November 1944= Barthel Schink notices the guards massing outside and realizes he doesn't have long to live so he tells Miriam the Shard's location and orders her to take it to the Assassins in Paris despite her reluctance and lack of knowledge about the Assassins because of her family connections guaranteeing her release. Then 13 then current and former male members of the Ehrenfelder Gruppe, (9 adults and 6 teenagers including Barthel Schink) were publically hanged in a residential next to the Ehrenfeld train station without trial officially on charges of 5 counts of murder, (including the head of the Cologne Gestapo) and planning to blow up the ELDE Haus. Later that day a Gestapo officer brags about it to Mariam Kurtz in order to get her to give up the Shard's location but she sees through the attempt.
The Templars may have let the Nazis discover and use the Shard to test the direct uses the artifact could have, like in 1943 the Philadelphia Project.