The one that comes to mind immediately and it is somewhere in 1 Samuel probably around the seventeenth chapter or so is when David was going to come against the Philistine giant and he said, "Is there not a cause?" There are times when God said to come against an enemy and gave whatever king was in power in Israel instruction to prepare for battle, he told David this, he told Saul this and many other kings. I would study 1 and 2 Samuel, 1 and 2 Kings and 1 and 2 chronicles for more on this. But if I were you I would not go into the military with idea that you will die in battle. Pray a hedge of protection over yourself. God protected David against insurmountable odds and He can protect you too.