Answer: Germany unconditional support sent to Austria for any action against Serbia
Explanation: After the assassination in Sarajevo on June 28, 1914, Austria Hungary sought the support from Germany, in an attempt to attack Serbia, and if Russia stood on the side of Serbia. German Emperor William II, on July 6, 1914, sent a telegram, along with his chancellor, the so-called blank check to Austria. It was Germany's promise of unconditional support to Austria, for any action against Serbia for the purpose of punishment for the committed assassination.
That's why this telegram of support is called a blank check, because Germany wanted Serbia to be punished at all costs, and every action of Austria, whatever it was, will have German support, which has left this telegram in history recorded as infamous.
