Franco prussian war.during the franco prussian war, germany was able to acquire the cities of alsacre and loraine from france
System of alliances.germany and Australia hungary joined to form the dual alliance while britain france and japan formed the tripple entente
Asssasination of franz ferdinand.franz ferdinand from austria hungary was killed by a serbia which led to declaration of war between different nations from the two powers
Rise of nationalism.in Europe no country wanted to feel less.German for example thought they were a superior race
Arms race.different countries started manufacturing weapons to compete with others which caused tention among the nations in Europe