I understand why being second class citizens is not a pleasant thing, but for almost our entire history, including in the times of the Gemara, that’s what we have been. However a message of peace and general avoidance of war was still preached. Is being a second class citizen something worth killing and leading to death for, or is it just another feeling of modern nationalism that needs to be satisfied?

Exile is not what Judaism is about, but an unfortunate and temporary curse and punishment: "Because of our sins we were exiled from our Land… [please] return us from the gentile nations, and our dispersed from the four corners of the earth, and return us to our Land" (Festival Musaf). God's promise to give the Land of Israel to the People of Israel, is one of the major themes of the Tanach. That was the goal of leaving Egypt that we celebrate now on Pesach (otherwise, God could have freed us without taking us out!, see Ya'avetz on Siddur, Nodeh L'cha on Birkat HaMazon), that was the dream of Moshe, realized by Joshua, Samuel, David and the kings, to be an independent Holy Nation, speaking the Holy Language, living in the Holy Land. It's simply denying reality to suggest that Jewish nationalism is a modern invention, when it's clearly the goal of the Jewish People, to be a nation (!) which is a "Light for the Nations". Whenever that classic term is used, it's in the context of the Jewish Nation [=State] exemplifying how other nations should also live and run their countries (Yishayau 42 and 49). Those who didn't understand that we need a Jewish State with a Jewish army before the Holocaust, definitely understood it, afterwards. Being a "2nd class citizen" in a modern technological context is more than simply "unpleasant": my father-in-law's entire community of Stanislav was gassed in cold blood. The State of Israel is the solution to having Jews killed, and not, as you suggested, the problem or the cause. Yes, Zionism has seen 26,000 victims of war and terror, where each and every one is truly a tragedy, yet objectively, those 140 years (!) of Zionism, and that number of casualties is less than 1 week (!) in Auschwitz. It's also important to stress that when an additional 1.2 million Jews wanted to leave Soviet Russia, and 70,000 Jews needed to get out of Ethiopia, and another 200,000 were chased away from Yemen, Iraq, and Algeria, they now had where to run! If we would have had a Jewish State just 8 short years earlier, the 6,000,000 would have had refuge. Throughout the entire Tanach, the norm (!) is to fight in defense and risk our lives for the Jewish People and our Land, rather than to be butchered ten-fold in exile. The Maharal (Netzach Yisrael, ch. 1) writes that one of the biggest tragedies of exile, is that the abnormal situation of Jews "living under foreign rule in a foreign land" as 2nd class citizens, is mistakenly accepted as "normal". The gentiles logically proclaim, that if the Jewish God cannot protect His Chosen People, apparently He's not the "real" God! This is what's tragically termed: Chilul Hashem (desecration of His Name, see Yehezkel 36, 20; Tehilim 42, 4 ), or in modern English: "Where was God during the Holocaust?". Conversely our national (!) return to Israel is called there (Yechezkel, ibid) a Kiddush Hashem (Sanctifying God's Name). The Six-Day-War showed the world that the God of Israel is "alive and well" and that we are still the Chosen People, but even those miraculous victories were nevertheless, dependent on a certain price of self-sacrifice (for as I wrote previously, God stopped doing super-natural miracles already 2,500 years ago, enabling us more Free Will). There is only prophecy when the Jews are in Israel, and most of the mitzvot in the Torah, can only be observed here. The Torah addresses us as a nation living among Jews, where Shabbat is the national day of rest, and Pesach, Yom Kippur and Chanukah are the national standard and culture. Where we are all brothers and national unity is a religious obligation and norm. I strongly suggest you learn more Jewish history and Judaism in general, and you will understand all the more why the Tanach calls for all Jews to live together in the Jewish State in the Land of Israel, not just out of necessity, but out of ideal!