The English word peace is a rather inadequate translation for the Hebrew shalom. Peace in English has in it the idea of the absence of conflict. This is not really what shalom truly means. It is a very complicated concept. In it is contained seven nuances of meaning.
As an absence of physical conflict it used in the historical book at the end of hostilities.
And Joshua made peace with them, and made a covenant with them, to let them live; and the leaders of the congregation swore to them. Josh. 9:15
However most of the verses we think about we think of as peace or shalom are verses of peace between man and God. In these cases shalom is that realization that when one steps out into the conflict and all the flaming darts of the evil one come our way, we are absolutely sure that all is well. We may indeed lose our lives but that is not a problem as our lives where forfeit the moment we decided to walk with our Lord.
If then you have been raised with Christ, seek the things that are above, where Christ is, seated at the right hand of God. 2 Set your minds on things that are above, not on things that are on earth. 3 For you have died, and your life is hid with Christ in God. 4 When Christ who is our life appears, then you also will appear with him in glory. Col. 3:1-4
Shalom is that calm assurance that in the heat of battle no matter what comes our way we will never lose our souls.
My sheep hear my voice, and I know them, and they follow me; 28 and I give them eternal life, and they shall never perish, and no one shall snatch them out of my hand. John 10:27-28
Shalom is not just the absence of physical conflict, it is the absence of internal conflict.
“Do not think that I have come to bring peace on earth; I have not come to bring peace, but a sword. Matt. 10:34
It is not the peace between men but rather peace between those men who are willing and their God. So Sally forth into battle, there is nothing to fear.
Peace I leave with you; my peace I give to you; not as the world gives do I give to you. Let not your hearts be troubled, neither let them be afraid. John 14:27