An example for all generations:
Joshua 8:24 When Israel had finished slaughtering all the inhabitants of Ai in the open wilderness where they pursued them, and when all of them to the very last had fallen by the edge of the sword, all Israel returned to Ai, and attacked it with the edge of the sword. 25 The total of those who fell that day, both men and women, was twelve thousand—all the people of Ai. 26 For Joshua did not draw back his hand, with which he stretched out the sword, until he had utterly destroyed all the inhabitants of Ai. 27 Only the livestock and the spoil of that city Israel took as their booty, according to the word of the Lord that he had issued to Joshua. 28 So Joshua burned Ai, and made it forever a heap of ruins, as it is to this day. 29 And he hanged the king of Ai on a tree until evening; and at sunset Joshua commanded, and they took his body down from the tree, threw it down at the entrance of the gate of the city, and raised over it a great heap of stones, which stands there to this day.
IF we do not become vigilant in this manner and just wait for Moshiach to come or a special King to take the throne of Israel, then our enemies will conquer our land and lead us into captivity the same was as the CHaldeans did 2500 years ago.
And, if we were to sit and wait and show compassion on the Germans, not bombing their homes, women and children and wiping them out , very likely, Hitler's Germany would have become the most powerful nation in the world today. There would have been no Jews left in Europe or in the Middle East, as "Palestine" Would have been his colony under the leadership of Mufti Amin Al Husseini and his descendants.
Also, does anyone remember when the Ally soldiers liberated the Concentration Camps and then lined up their German prisoners against the wall and executed all of them after being terrorized at the horror they saw at the camps? Would any Jewish person contend that these soldiers were wrong to kill these German men who were their prisoners? Would any Jew say this was a ruthless act against these young German men, who themselves, brutalized and torutred Jewish and other prisoners in their Death Camps?
https://www.youtube.com/watch?v=HD4bDHTHdpUDachau Concentration Camp Liberation Massacre by Allies
https://www.youtube.com/watch?v=1fA5_kS9lbUMaybe we can have some Rabbis write long papers about the crimes committed against the Germans, as they write about the crimes committed against the "Palestinians".
As for me, I am all for executing all of our enemies, German (Nazi era) and Palestinian (Fatah/Hamas Arabs). I will not sympathize nor do I think we shoudl wait for a righteous leader to lead the invasion. If we must fight a guerrilla war or even find a secular leader whose goal is to protect the Israeli people against the evil people who seek our destruction, then so be it. Better even a non-religious Jew who will help rid of Israel of its enemies than a religious Jew who will seek to appease them and empower them.
Remember, the USA, itself, was formed from an uprising against a corrupt and ruthless monarchy leadership.