Rav Tzvi Yehuda Hakohen Kook, saw the terrible destruction of the Shoah in the context of the great construction of the Redemption. While the Exile was being all but destroyed, he Nation of Israel was being built up in its homeland.
In the past few years, nations have come upon us and demanded that we relinquish portions of the Land of Israel to strangers. This is one of the calamities concerning which we are supposed to fast and cry out to God about.