Final answer:
Tensions escalated between Austria-Hungary and Serbia after the assassination of Franz Ferdinand, leading to diplomatic communications and preparations for war.
Step-by-step explanation:
In the month between the assassination of Franz Ferdinand and when Austria issued its ultimatum to Serbia, tensions between the two countries escalated. Austria-Hungary blamed Serbia for the assassination and used it as an opportunity to assert their dominance in the region. During this time, diplomatic communications were exchanged, alliances were solidified, and preparations for war were made.
Learn more about Escalating tensions between Austria-Hungary and Serbia after the assassination of Franz Ferdinand