Can I die fighting for my country, even against Muslim attackers?

**Can a Muslim man die for his country?** If it is attacked by a nation that has **both Muslims and non-Muslims in the army**, although the non-Muslims are the majority and are the leaders of the country. When it comes to war the enemy will be an enemy whether Muslim or non-Muslim and the majority of the enemy is non-Muslims so my question is: **As a Muslim is it permissible to join that war to defend my people and my home?** Secondly **if I kill a Muslim enemy without knowledge**, will I go to hell for that? Lastly **if I capture a Muslim brother who was with the enemy**, do I have to consider him as a hypocrite and kill him or I keep him as a hostage until the war ends?