What happened August-September 1914?

In August-September 1914, the First World War began following the assassination of Archduke Franz Ferdinand of Austria-Hungary. Germany declared war on Russia on August 1, and soon after, on August 3, it declared war on France. The German army executed its Schlieffen Plan, invading Belgium to outflank French defenses, which prompted Britain to declare war on Germany on August 4. This period marked the start of extensive military engagements, including the Battle of the Frontiers and the First Battle of the Marne, setting the stage for a prolonged and devastating conflict.