According to Osho, the very question is misplaced: as long as nations exist, attack and defense ensure endless turmoil. Neither taking up the sword nor refusing it has ended suffering. He refuses the physical sword and urges a subtler one - erasing mental and political borders, dissolving nationalism, and affirming the earth as one. Only by ending the lines that divide us will wars cease; otherwise, peace-talk merely fuels preparation for war.
Instead of asking how to fight for a country, stop making countries in your mind so there is no enemy to fight.