I have many great moments, but the greatest one I think was a few years ago (most likely 2013) when there was still recap for Minas Tirith. Gondor was beaten back to gate 5, which was almost definitely a lose back then (It still is, but at that time Gate 5 was even more undefendable). I was playing on Gondor and I didn't want to lose, so I assembled a commando team to get it back: polarnik, lotrloz, electric_ice777, myself, and I think 2-3 more soldiers. We beat Mordor all the way back to Gate 2 despite the sheer number of trolls they had as there was no troll cap back then, and Gate 2 at that time was almost impossible to take for either side. We also had to fend off the Mordor army who were trapped behind us when we took the gates and the Mordor army in front of us, so essentially we had to fight on both sides until the rest of Gondor was able to reach us. After that, we beat Mordor back to the main gate so hard it was nearly spawnkilling (we didn't camp the spawn, but we surrounded all the exits). In the last 10 minutes they did remove us from the main gate, but by that time our constructors had already built a fortress halfway between the gates which was nearly impossible to take, and the game ended there.
My second greatest moment would be meeting dwight333 when he was commanding a group of 'Ithilien rangers' on the ridge of Gate 2 in Tirith, again long ago. That was where I met dwight for the first time and I was quite impressed, and most of you especially those from Ilthilien know how that worked out.