I'm nearing the end of my HE campaign, which while fun, has not been nearly as satisfying as previous campaigns with Silvan Elves and Rohan. I find myself struggling to maintain more than 2.5 stacks with my economy, which is barely enough to keep any forward momentum against my final enemies (focused on finishing Mordor, dont know if I will have time to get to Harad and Rhun with only about 95 turns to go).
My current empire: I have established a crescent-shaped empire in the west which includes everything from: HE starting cities on the coast; Allimir, Eryn Vorn, Argond, Lond Daer, Duneard, Talsir, Lond Angren, and Isengard, Moria, Byrig, Ostin-Edhil and Imraldis on the other end. The OOM and Isengard settlements have provided great profit centers and recruitment sources (they are pretty much the sole source of my top tier troops right now). The settlements further west (even my starting ones) have been slow to grow (out of my 4 starting cities on the western coast only Mithlond is capable of producing top tier troops) and at this point are too far from the war front to be of any real use (though they are providing Linden Spears which have been instrumental in dealing with the numerous trolls I have encountered, a much underrated unit IMO). As Gondor was getting tag-teamed by Mordor and Harad in the mid-game (they had lost Cair Andros, Henneth Annun, W. and E. Osgiliath) I sent 2 expeditionary stacks to retake those lands and colonize to create a buffer between Mordo and Gondor. That operation was a slug fest, and very tedious since my line of reinforcement was getting stretched, but it did work in the long run. Gondor has been able to hold the Harad stack spam at bay (though they will need my help eventually) and I am now getting to the point where I can recruit basic troops from these colonized cities/castles (though I still rely on lengthy marches from my western settlements to reinforce my top tier units). From this new "eastern" kingdom i have struck out to conquer Minas Morgul and Cirith Ungol which has further reduced Mordor's recruitment cities. The end is near for Mordor, but alas their armies are still strong and plentiful. They have 1-2 stacks blocking my advance from the Cirith Ungol pass and they still send forth numerous armies from the Black Gates to battle Rohan for control of Malgalad (Rohan is losing horribly but thankfully are diverting a good bit of Mordor's attention away from my own operations).
The challenge I face is two-fold:
1) My armies rely on reinforcements from my western cities of Moria, Isengard, Imraldis, and even further (Forlond, Harlond) for my Linden Spears (my only AP unit I currently have access to). After several major battles, I have to halt my offensive operations in order to allow reinforcements to come in (I have my western cities constantly recruiting new units, but the march time means I still have to wait before they get to the front).
2) My economy is working, but not well enough. My starting cities have been very slow to grow (only Mithlond is a small city at this point). This coupled with my having many mediocre governors (I probably need to make a dedicated effort to train better governors for the next campaign) means that my cash flows are barely high enough to sustain my operation requirements. Don't get me wrong...I have about $70k gold right now, and I haven't dipped below $63k for quite some time. But once i start to mobilize more than 1-2 field armies and my units start leaving their garrison (and free upkeep), I struggle to maintain a positive net income. If I were to put 3 full stacks into the field right now (which is what I sorely need) I would likely be losing about $2k-$3k (recruitment + buildings + wages) gold every turn, which I can sustain for a few turns, but not for the long term.
So this is what I mean when I say am fighting with a glass hammer as the HE. My units are supreme on the battlefield; their ranged attacks can decimate most enemy armies before they even reach my ranks, and their melee can overcome the rest....but I always take casualties (at least several hundred) due to the fact that I am now fighting catapults (which are way too accurate IMHO) and fully armored trolls. I know how to deal with these threats, but short of a chokepoint battle or fighting from very high ground, casualties are inevitable. And when I take those casualties is when I have to pause my offensive operation to recruit, reinforce, which costs me time and money. I simply don't have enough money and troops readily available to keep up a constant offense...it's honestly to the point where I may defeat Mordor just before the game turns run out.
When I started this campaign, I had grand visions of conquering a nice little empire out of Moria's and Isengard's former holdings (which I did for the most part) and then sitting back and letting my cities (and economy grow) so that i could build up some fleets and nice powerful stacks to sail to either Harad or Mordor and launch behind-the-lines Inchon style attacks....that plan never came to fruition. As soon as I had defeated Isengard and Moria (which happened by the mid-game) Eriador needed my help with Gungabad. Once that was done, my spies revealed that Gondor was literally about to lose everything to a double pronged Mordor/harad Offensive. I firmly believe in keeping Gondor alive for lore and strategic reasons (they keep Harad distracted for the end game) so I sent all the armies I could muster (2 full stacks) which started to put me in the red to save Gondor (as previously mentioned). That worked, but at that point I was committed to full out slug-fest with Mordor, and my chance to lay low and focus on economics was gone...which is where I presently am.
My lessons learned for HE going forward:
1) Work on developing good governors (put them in cities where economic buildings are built, turn taxes to VH for last turn of build, keep taxes low to medium for all other turns, ect.)
2) Defeat Isengard and Moria by end of early game. Either one can become a stream-rolling power and quickly take out allied factions so eliminate them early on before they have a chance to grow. I definitely let both powers grow too big, and my fights with them kept me busy well into the mid-game.
3) Keep an eye on side fights (Gungabad and Mordor) and send money and/or troops to reinforce or aid allies before they get into dire straights.
4) Keep taxes low for key cities early on to allow for quicker growth. All of my starting cities (minus Mithlond) are still only large towns at this point in the end game...they should be small to large cities by now, but I fluctuated the taxes to compensate for income issues and used mediocre governors.
5) Gondor's survival is the key to a healthy end game. If they go, Harad and Mordor gain major lands and income/recruitment sources and you pretty much have 2 huge superpowers to deal with for the end-game....not saying its impossible to overcome that, but it's not the preferred way for sure.
6) Always recruit Linden Spears when they are available. Many HE players say they're too expensive and have too limited recruitment to be useful...I disagree. They are the only early-mid game units that have AP ( I still haven't unlocked smiths of Egregion) and will prove their worth when you start having to contend with 2-3 armored trolls per enemy stack.
7) Plan your recruitment cities ahead of time. If I had used some foresight, I would have conquered W. Osgiliath or Cair Andros 10-20 turns sooner than when I actually did. Instead I waited until Mordor was besieging Minas Tirith. Elves and elven culture take for ever to recruit and propagate....start that process earlier vice later.
Anyway, that's my story. Maybe some others on here can add their own experiences with HE in the end game?