Before the start of WW1 a two treaty's were signed between 6 countries. Germany, Austria-Hungary and Italy made up the Triple Alliance. Britain, France and Russia made up the triple Entente.
The treaty's stated that if one of the countries in the treaty felt threatened by another country then the other two countries in that alliance would have to protect that country immediately.
For example if Germany felt threatened by France then Italy and Austria-Hungary would have to protect and assist Germany.
The assassination of Franz Ferdinand at the hands of Gavrilo Princip was the trigger that started WW1. After Franz Ferdinand was assassinated Austria-Hungary declared war on Serbia. A month later Germany signed a secret treaty with the Ottoman Empire. The very next day Germany declared war on France. The day after that Germany invaded Belgium meaning that Britain, who were close friends with Belgium, declared war on Germany. Six days later Austria-Hungary invaded Russia.
All of these major moments which happened within 3 months of each other meant that the bloodiest war the world had ever seen was imminent.
The treaty's stated that if one of the countries in the treaty felt threatened by another country then the other two countries in that alliance would have to protect that country immediately.
For example if Germany felt threatened by France then Italy and Austria-Hungary would have to protect and assist Germany.
The assassination of Franz Ferdinand at the hands of Gavrilo Princip was the trigger that started WW1. After Franz Ferdinand was assassinated Austria-Hungary declared war on Serbia. A month later Germany signed a secret treaty with the Ottoman Empire. The very next day Germany declared war on France. The day after that Germany invaded Belgium meaning that Britain, who were close friends with Belgium, declared war on Germany. Six days later Austria-Hungary invaded Russia.
All of these major moments which happened within 3 months of each other meant that the bloodiest war the world had ever seen was imminent.