Answer: German guarantees that will help Austria Hungary in case Russia enters the war on the side of Serbia
Explanation: After the assassination of Archduke Ferdinand in Sarajevo on June 28, 1914, the government of Austria Hungary was determined to declare the war on Serbia, but it was necessary to secure ally in case Russia stood in defense and assistance to Serbia. Thus, Austria Hungary sought assistance and guarantees from Germany to help if Russia entered the war on the side of Serbia. Germany pledged its support and encouraged Austria to attack Serbia, after which, with the non-acceptance of the Austrian ultimatum by the Serbs, the war was declared on Serbia on July 28, 1914.
Thirteen Colonies” is shorthand for the English-speaking colonies arrayed along the east coast of North America, which rebelled against Britain in 1775-83.