With reference to classical myth, where the olivebranch was a symbol of peace and prosperity, merging with Biblical allusion to Genesis 8:11, where a dove returns to Noah's ark as a sign that the Flood is subsiding.
His remarks came after Britain offered a diplomatic olive branch to Iran earlier in the day to try to secure an early release of the prisoners. - The Observer, Iran snubs UK olive branch, 01/04/2007 
I come bearing an olive branch in one hand, and the freedom fighter's gun in the other. Do not let the olive branch fall from my hand - Yasser Arafat