Question

Countries in Europe were very proud of themselves and would defend their country as well as they could. This is known as

Answer 1

When having pride of a certain country, it is called nationalism. 

Too much nationalism can cause problems, one of the causes of WW1 was nationalism. 

Answer 2

I'd say its patriotism.

patriotism: love for or devotion to one's country.

i was going to say nationalism but the dictionary definition of nationalism (nationalism: patriotic feeling, principles, or efforts) is basically referring back to patriotism, so :-)