The first Great Leader I got in my current game was in 2200 AD. Of course, I stayed out of war as much as possible, and I'm playing on Warlord level.
But as for overall tactics during wartime...
I prefer playing on maps with small Archipelagos, since this splits civilizations up for a good amount of time, like IRL - the Europeans never found America for a good long time (ignoring the Vikings, who didn't do a whole lot in America AFAIK.), and since this limits the number of civilizations who try to box me in before I get going...
In the early game, I expand as fast as possible, taking over as much land as I can as fast as I can, especially to get important early resources like Horses and Iron.
If I run into anyone else on my island, I try to keep expanding while retooling a couple of my oldest cities into building archers(I've noticed I don't need swordsmen or horsemen to conquer early on, a huge amount of archers is sufficient to smash through early defenses.) Once all the available land is taken up, I switch to building archers in most of my cities, and begin my attack by moving forces onto any of their strategic resources I can access, so they can't build swordsmen to fight back with.
In my current game, I started on an island with the French, and when the initial colonization rush had ended, I found that the french were in possession of two iron and a horse or two, and I had none. I moved as fast as I could to occupy their westmost iron with a military unit so they could not use it, and then to move up several armies of archers to begin the attack in earnest. I took their capital and the cities in the center of their empire immediately. Their other iron was in the east, and as a result of my splitting their empire and taking the west iron, only half their empire had iron. I wasted no time smashing that half and taking that iron as well, and then smashing the rest.
After that early conquest, I pretty much stayed at peace until the 1700s or so. Around then the only civilizations left in the game were:
Me (English)
Egyptians
Iroquois
Greeks
Romans
Germans
Oh, and somebody or other who had all of one city. The Zulus or Aztecs, maybe. I've forgotten.
The Germans got their butts kicked by somebody or other (They were on the other side of the world, so I didn't pay much attention).
There was then a rush to sign Mutual Protection Pacts, leading to there being 3 or so groups of nations. There was a series of minor skirmishes among the AIs over the next hundred years, and eventually I arranged mutual protection pacts and right of passage agreements with the Egyptians, Greeks, and Iroquois, and we collectively attacked the Romans. They were wiped off the face of the earth, and I got a good deal of their territory in the bargin.
Around this time, I finished researching and made the switch to Communism, from Democracy, and my cities on other islands suddenly became useful.
After destroying the Romans, I sent a galleon filled with cavalry to the zulu/aztec/whoever city, dropped them off, and took the city, eliminating the civilization, the next turn. The hardest part of conquering them was figuring out where their city was
.
Now, the only remaining AIs were the Egyptians, Iroquois, and the Greeks. The Grand Alliance of us four disintegrated, with the Egyptians and Iroquois teaming up against the Greeks, and me staying out of it. Neither side made any inroads against the other.
The game went on for a bit with those minor wars flaring up for a bit and then settling down again, until eventually I agreed to mutual protection pacts with the Egyptians and the Iroquois, and attacked the Greeks myself. I took about 1/3 of their home continent, and about 1/2 of another of their continents before I agreed to a peace treaty, and severed my MPPs with the other two civs so as not to be pulled back into war with the greeks (I was running low on troops and the greeks appeared to be regrouping with large numbers of armies in an attempt to retake the lost part of their homeland.)
I stopped paying attention to the greeks for a while, and was startled a while later when I was informed the Greeks had been wiped out by the Egyptians. I looked at the map, and thought back to what had happened, and apparently right as the Greeks were regrouping to counterattack me, the Egyptians must have attacked the other side of the Greek home continent and rolled up several Greek cities just after I negotiated peace, before the Greeks could get their armies back to the other side of the continent.
Well, as it turned out after that war ended, the Egyptians held the former Greek territory which I had ceased invading, leaving them firmly in the #1 spot in both power and territory. I was in 2nd place, and the only other remaining civilization was the Iroquois.
The "game ended" in 2050 with the retirement, just at the beginning of the Modern age, but I kept playing because I'd never gotten this far before. :P
After the destruction of the Greeks, I did my very best to stay at peace with everyone else because (1) I needed a strategic resource I was trading with the Iroquois for, and (2) The egyptians were so powerful they could smash me if they wanted, or so I thought at the time. (I did my best to stay at peace until then, as well, because I was trading with the Greeks for strategic resources as well, that is, until I declared war and took said resources from them. :P)
After the development of nuclear weapons, the Egyptians got tired of me, and declared war out of the blue and started off attacking with with tanks in the former Greek islands.
My first act was to immediately entice the Iroquois to ally with me against the Egyptians, to take some of the pressure off me.
My homeland was well-fortified, but the rest of my lands weren't, so I had to hurry to fortify them so they couldn't be rolled up by the Egyptians. Once that was accomplished and the Egyptians were fighting a two-front war (They had territory on the same continent as the Iroquois, plus both civs had additional islands in addition to their shared one), I began building battleships, tactical nukes (Once I'd finished researching the tech for nukes, of course.), and a few nuclear submarines.
I didn't use the nukes at first, since the Egyptians had several ICBMs of their own and using them would only call down the wrath of ra (The egyptian sun god. Appropriate for nuclear explosion, da?) on my most populous cities...
The fighting mostly centered around the Greek lands for a good while, and eventually I united the smaller one - the greek homeland, however, remains divided as it was at the end of the Greek wars, partially due to a mountain range separating mine and the Egyptian cities.
But once ICBMs had been developed, and I had several, plus tactical nukes in nuke subs, I nuked the Egyptian capital, knocking out all roads to the city and to the coastal hills which bordered said capital, and I offloaded an army of modern armor and a few mech inf. My battleships moved in and began bombarding the Egyptian strategic resources, knocking out their roads. I took their capital, and several more cities in the area.
However, they did strike my 3 best cities with ICBMs immediately after my nuclear strike, and I detailed workers to clean up ASAP, but that didn't hurt my overall war output that much (I have a lot of good production cities, and corruption isn't that big a problem in Communism.).
Currently, I have destroyed the roads to every single Egyptian resource, and have left them unable to build just about anything modern. My land forces have run out currently (but so have theirs), as I've been focusing on building battleships recently.
Also, I've dropped around 6 more nukes, mostly ICBMs, on Egyptian cities during the war, mainly to knock out places where they'd built a city right next to two strategic resources and to do some damage (these were usually their better cities.) I also nuked their new capital for good measure, although I didn't invade it.
I've noticed that some units may survive the nuclear attack, so one can't just paradrop in (or move howitzers in by rail :P) anymore like in Civ II.
For bombard units, I have not once built an artillery unit this game, as they were useless in my previous games, I use only battleships and occasionally jet fighters or bombers. I haven't built a lot of bombers, as they haven't seemed to work that well so far.
When the Egyptian war began, it looked for sure like I would be losing soon, but on the contrary, I turned them back, and then essentially destroyed their ability to build modern units. In a few more years, I expect to begin moving large groups of Modern Armor over to their home contininent, which I already own 1/5 of, in order to smash what little resistance is there. From there, I'll be taking over the rest of their land, and then I'll turn on the Iroquois.
By the way, the Egyptians did manage to take the Iroquois territory on their home continent, prior to my invasion.
