I joined w18 as one of my friends suggested I give it a go as it required very little time to play (yeah, right!)
I was in K51, he was in K45 and was baron of a small tribe "Roman Republic" (_RR_). He then moved to a family tribe "Kingdom Hearts K45" (KH~K45) and I, with a dizzying 776 points, followed (Post script: I suspect both tribes were very early casualties of the expansion of "The Elite Brotherhood")
I elected to join a local tribe (~TLoT~) immediately before by first conquer. One of my first "diplomatic" acts was to define a boundary between ~TLoT~ and the neighbouring tribe (Delian I believe). ~TLoT~ grew rapidly to dominate the eastern 2/3rds of K51. It was at that time that Delian (led by Neoptolemus, supported by Wolfhunt1) swore fealty to RKN to become RKN-D. That meant that we had RKN-D to the west, RKN to the north (K41), The FFDx to the east (K52) and Panthx and ARD to the south (K61). K61 seemed the best option, until the inhabitants joined TWA as TWA-W. Declaring war on TWA, RKN or FFDx seemed suicidal so my second major diplomatic act was to arrange the merger of RKN-D and ~TLoT~ to form RKN-51.
The first acts of RKN-51 were to secure its western border by moving into K50 verses "Warriors of War" (~W.W~) and to engage in a land grab to the south and south west (verses ARD et al). It was during the push along the western rim that we encountered Fire Nation (~FN~) who, after some negotiation, joined RKN as RKN-SA. RKN-51 had been renamed RKN-W and started pushing east through K52 and Legion.
Eventually Neo was appointed to the Quad (which required him to move to RKN), leaving Wolfhunt1 and me to lead RKN-W. That prompted a restructing of the family so that the tribes were regarded as equal and the members of the Quad could be drawn from any of the tribes (and still remain in those tribes). We later reorganised to according to geography and direction of advance which meant that I moved into RKN-C (#2 tribe behind MM), later becoming the tribe's Duke. RKN-C made rapid progress though Legion's K52 presence (acquiring a couple of key players such as lackmanblue & scguillaume during Christmas 2008).
At that time Adanouch invited me down to K62/K63/K64 to help fight |TF|I & Legion (Moonchild, Sir Deano etc) just after Christmas.
In May of 2009 the "UA" council determined that TWA and RKN would merge. I believe Zurtle initially suggested Apocalypse at which I came up with the horseman idea. TWA-N3 became Apoc-D (which RKN-C merged into), TWA-S became Apoc-W, TWA-N1 became Apoc-C (which RKN-N merged into) and RKN-S became Apoc-F. I had hoped TWA-W would merge into Apoc-F but they didn't and became Apoc-N :-(
Apoc's progression through the core is well documented. Until recently my focus has been eastwards along the 6x Ks. Over the course of my time in W18 I have gained dominance in 3 Ks (51, 64 & 65). I intend to add one more to the collection before the world ends
Although I have rimmed a few dozen players during my time I can't claim to have been solely responsible for rimming a "world" player. That said probably one of my most rewarding conflicts was against AA after he forgot which side he was on while allegedly spying on MM for Apoc. AA wasn't a particularly tough opponent but boy did he blub as he was taken down
Postscript
Sorry - forgot to respond to all of the OP's questions!
What Ks you had major presences in along the way I sort of answered this but, for the sake of completeness, I have had and maintained major (>50 vills) presences in K51, K52, K61, K63, K64, K65, K75, K87 (#1 in K51, K64, K65 and...)
What leadership roles you had in any tribes... Baron in ~TLoT~, Duke in RKN-51 (now Apoc-F), Duke in RKN-C, UA council member, Duke in Apoc-D/Apoc.
Epic successes and failures... Thankfully more successes than failures.
Probably the major successes have been diplomacy/leadership orientated. Just one more to knock down: Part of the team that won W18
On a personal level I was very happy to repel the all-out offensive on me by TF that was led by Cal- without the loss of a single village (despite some pretty close quarters nobling attempts). I like to think that their failure to make even a minor dent in me precipitated Cal- & Rattlesnake8's deletion (they deleted very soon after the last attack foundered on my walls). Perhaps one of my most unexpected and rewarding experiences was while I was sitting LORD77en who was based in K55 (at that time deep in MM territory) and resisted the attentions of all the surrounding players, including the
vastly overrated LLT, and allowed a number of Apoc players (including Zurtle) to gain a foothold in the K.
On the failure front failure to stop the self destruction of Apoc-W (now TF) was a low point as was the failure to get willmn5095 (and a couple of other TF players) to come back to Apoc, despite the writing being on the wall for TF and Cal- & Rattlesnake8 deleting. On a personal level my attention level has waxed and waned throughout my time on w18 which has meant I have alternated between surgical (w.r.t. timing nukes/trains/support) and completely gash. Not exactly "epic" but still a little disappointing!