No, frontier is any unexplored area which is why space may be the final "frontier".
That would be a battle.
It is usually known as a battle.
You, talk to them, and then fight them. And win.
Allied armies are Armies from different countries that are working on the same side. Two or more countries may come together to fight a common enemy, this would make them allied armies.
We had fought Japan because they had invaded France
for avoid a battle between two armies.
Nowhere. You don't bury survivors. The survivors don't get buried.
Don't frickin use this website!
Open field warfare the land where two sides meet for war and fight.
Engaged in that case means to be involved in battle. When two armies meet on a battlefield they are said to have "engaged" each other.
crossroads means were two Moon Piez meet up and fight people.
Open field warfare the land where two sides meet for war and fight.