Why did european nations increasingly form allies in the 1900s

  To try and combat other nation's powers, to protect themselves from attack, for better economic opportunities, to ally themselves with the stronger person, etc.

Bob: coke is baby pandas.jim: what? how do you figure that coke is baby pandas? bob: because this book says so.jim: how do we know the book is correct? bob: because it says that coke is baby pandas.jim: how does that prove the book's accuracy? bob: because it's statement involving coke and baby pandas is correct, therefore it is accurate.jim: how do we know that it's correct? bob: because we have concluded that the book is accurate, and therefore the statement is correct.therefore, coke is baby pandas.

Advances in learning and technology made long ocean voyages possible