- On the Eastern Front, the northern wing of the Austro-Hungarian 2nd Army pushes through the Russian position at Podkamien, and forces the southern wing of the Russian 8th Army to fall back to the Ikwa River. As this advance is occurring, the Russians undertake their first major counteroffensive to the south today when elements of the Russian XI Corps advance this afternoon out of bridgeheads they had maintained on the west bank of the Sereth River just west of Trombowla. The advance strikes the inner wings of Südarmee (to the north) and the Austro-Hungarian 7th Army at a moment when the attention of their commanders are on attacks about to be launched elsewhere. On the southern wing of Südarmee, the Russians are able to push into the poorly-constructed defences of the Austro-Hungarian 55th Division, and counterattacks by the corps' reserve are unable to restore the situation. Just to the south the Russians are able to break through between the Austro-Hungarian 131st Brigade and 7th Division at Janow.
|The Russian counteroffensive along the Sereth River, Sept. 6th to 8th, 1915.|
- With the approval of his government, Lieutenant-Colonel Ganchev signs the military convention at Pless by which Germany, Austria-Hungary, and Bulgaria agree to a five-year defensive treaty and the latter pledges to enter the war on the side of the former. For the campaign against Serbia, Germany and Austria-Hungary agree to commit six divisions each to an offensive against Serbia within thirty days, while Bulgaria will join the offensive within thirty-five days with four divisions. In return Bulgaria is promised Macedonia and additional Serbian territory east of the Morava River, and further should either Greece or Romania enter the war on the side of the Entente Bulgaria will be entitled to recover those lands lost in the Second Balkan War. The Germans agree to loan Bulgaria 200 million francs, while the latter agree to permit unimpeded transport of war material through Bulgarian territory to the Ottoman Empire. Finally, on the insistence of the Bulgarian government the convention stipulates that General Mackensen will be in overall command of the invasion of Serbia, a term as pleasing to Falkenhayn as it is upsetting to Conrad. Given the state of the Austro-Hungarian army and its abject failure in 1914 to conquer Serbia despite three separate offensives, it is entirely understandable that the Bulgarians want a German general to command the combined operation. Conrad naturally sees this (quite correctly) as an affront, given Austria-Hungary's view of the Balkans as falling within its sphere of influence, but he is in no position to object. It is also worth noting that on the German side the convention was negotiated and signed entirely by Falkenhayn and his staff - at no point was the civilian government of Germany involved in the decision, reflecting the growing power of the German army to dictate war policy within Germany.