1900 and 1902 proved to be the critical turns in the battle for control of the Airbase. Gandhi sent his main stack into combat there on the 1900 turn, and I slaughtered them to a man, with some losses. On the following turn, Roosevelt attacked with another major force of 20+ units, and I killed them all as well. It would not have been possible with my huge air force of bombers (15+) all hovering over the airbase, plus logistical support from all three of my carriers, each with their full component of three fighters. The fighting was bloody, but I held onto Eastern Airbase - and that was what really mattered. The AI discovery of Flight may even have been a break for me, as they stopped for two turns to upgrade all their cavs to gunships. That allowed me to mass defenders in the airbase just in the nick of time to hold onto it.
It's a funny world sometimes.
I did lose all my German possessions except Magyar in the process, but that was only a minor point. They tried their best to push me back into the sea, and came up a bit short. Now that my threat level was dialed up to full, I intended to make no more silly mistakes. Any city that can't be held will be razed to the ground and replaced with one of my own cities; I began queueing up some additional settlers just to have as many as I needed at hand. The Arabian counteroffensive was about to commence! 
It was my spies who began to turn the tide. I realized a little before 1900 that my spies could do more than just reveal tiles for me in the fog - they could pillage resources out of range of my air force too! A quick check of the world map revealed that there were a total of six oil sources on the other continent. Two were in the water to the south of Germany, where my navy was keeping work boats from hooking the resources up. Another was just south of Madras, in German territory, which I was keeping disconnected with my fighters. Then there was one in Roosevelt's borders far to the north, and two in the French jungles in the east. If I was having good success against the Germans with their oil disconnected, why not deny it to France and India as well?
As anyone who's played a Modern-era start in Multiplayer knows, oil is the lifeblood of a civ in the late game. Without oil, a civ can't build tanks, gunships, or any kind of plane. Frankly, the only reason I was still in this game was that I had managed to deny Germany oil for their panzers thus far. I blew up Nappy's first oil well in 1898; this cut off the supply he was sending to Gandhi. Then in the above shot, you see me taking out his own oil. My spy sent to get FDR's oil failed in her attack roll (70%), but I managed to cut off oil to the other three civs, and that made a huge difference! 
Even though I had already killed two major stacks from FDR in 1900 and 1902, he still had quite a lot units hanging around in Bengal, just to the north of the Airbase. With massive bomber support and some tricky moves from my workers, I hit him hard and burned the city to the ground!
Note the bizarre message saying that the borders of Bengal have expanded AFTER I raze the city, heh. (That's because I previously occupied this city and had already expanded borders there.) Bengal was unreachable at the start of my turn, but I grabbed three workers and had them build a rail on the circled desert tile, thus allowing the 2-move tanks to hit Bengal. Hooray for combat engineers!
In addition to wiping out Bengal, my destroyers and battleships found a major American naval force heading across the ocean in 1906, and sunk it to the last man. Another dozen American units went down to the bottom. I was keeping track of the demographics, and between 1902 and 1906, the American soldier count fell from 3565000 to 2937000 - a massive plumment on the power chart (I'll show a picture later). In other words, not even the AI civs could absorb these kind of losses turn after turn without suffering ill effects. In fact, Nappy even came begging for peace a couple turns later:
Look what he's willing to give me - Munich is a size 13 city, one of Germany's core cities! 
But I remember back to 1806, when Napoleon arrogantly declared war on me for little pretext. You started this war, and now you're trying to back out of it? No deal. This war will not end until one of our two sides is wiped from the face of the earth.
Nappy had one last stack left in the south, but it was weakening as I continued to bomb it turn after turn with my air power. I reoccupied Cologne in 1912, and the French charged out of Munich with their artillery to take it back. In a reprise of my earlier fight against Bismarck, they got Cologne back, but it opened the way to Munich:
Those are the last vestiges of Nappy's stack before it was wiped out. The French expeditionary force made several conquests in Germany, but they were now gassed and had overextended supply lines. I rapidly took Munich, Cologne (that poor city! 6th time it had changed sides), and the French junk city of Amiens. By the end of 1916, a single turn later, the battlefield in the south had changed dramatically:
I put a blue circle on the former location of Amiens; it only existed for about 5 turns, so I wasn't exactly mourning it. Slightly to the north, I finally just razed Munich and replaced it with my own city of Fez; with a forced artist specialist from Eiffel Tower's free broadcast towers (+4 culture) and Sistine's bonus specialist effect (+2 culture) and the broadcast tower boosting effect (+50% culture), I could get 9 culture there on the first turn. With a Hindu missionary on hand, that could be topped off to 10 culture for instant border expansion on the FIRST turn, with ZERO buildings rushed. Ha! Can't beat that combo! 
Razing and replacing meant I had much smaller cities, of course, but the gain was offset by being able to get instant border expansions, rather than having to wait 10 or so turns for the city to come out of resistance. I would repeat this pattern elsewhere.
Here you see the fortress I set up in the north:
By the same process just described, Bukhara expanded its borders in a single turn. Thanks to the peaks and cultural borders, nothing can get by this location. I was keeping a healthy garrison on hand here to protect this flank, while I carried out the huge wheeling movement in the south outlined a couple pages ago. Once Germany is gone, that will turn into a pincer movement striking from this direction as well.
Also note the razed cities to the northeast. Kolhapur's borders were in the way, so it had to go. Then the Americans founded a little junk city called Denver, so that had to go too. No more Mr. Nice Guy with trying to hold these cities. 532 is the number of the day. 
While FDR and Napoleon retreated to lick their wounds, for the moment I had total free run on the southern wastelands. As German cities were burned down in the south, my workers rushed into the opened gaps to lay down rails wherever they were needed. I kept flying in extra ones from the old continents, ready to have on standby if needed. Nothing bugs me worse than needing a worker and not having one at hand! Where tanks couldn't reach quickly enough, I would send my gunships ahead to do the dirty work along with air power support. Even if only one tank was able to reach a city, that was usually enough to take it along with help from gunships. That was the case at Berlin:
All my tanks attacked and used up their movement, except for a single crippled one with 7 health left. I used the four movement of gunships to kill the last few defenders, and my tank walked into the undefended city. That's why the printout is reading "your tank has destroyed an Abu Bakr!", since that Great Prophet was the top unit left in Berlin. You won't ever see that message for a Great Person unless a gunship takes out the actual defenders first.
Oh, and Abu Bakr was the Arab leader in Civ3. I found it ironic that he was being killed here by Saladin, the Arab leader in Civ4. You can't make this stuff up. 
Through some careful planning, I was in a position to take all three remaining German cities on the 1921 turn:
Here they are: Essen, Hamburg, and the offshore island of Dusseldorf. First I begin with a naval assault on Essen:
Despite some bad results there, I was able to pull in two additional gunships and take the city with relative ease. Hamburg then fell via a conventional attack, albeit with considerable air support. Finally, at Dusseldorf I was stymied by a lack of enough naval power to drop the cultural defenses. I killed one defender, but the remaining SAMs were too strong for the units in my sole transport.
Of course, that just means that the additional transport which was out of range in 1921 finished the job in 1922: 
It is now a two vs. THREE battle.
Here's what the power graph looked like in the wake of the German defeat:
FDR led in power for pretty much the whole game; you can see where it's blatantly obvious that his team got Assembly Line by the vertical leap in power. In the pink circle, you see where Gandhi was initially hit very hard by my attacks, and then actually recovered a bit during the AI counterattack. At roughly the same point, you see in the green circle where my Arabs fell considerably in power during the 1888-1890 turn, followed by a large upswing as I drafted replacements at a rapid pace. It should also be clear where the American and French stacks were killed off, judging by the massive fall in their power ratings. You can also see at the bottom where Bismarck's power dropped rapidly, leveled off for a while when I was on the defensive, and then nose-dived as I blitzed through him at the end.
As of 1920, I have reached #1 in total power, and I will not look back again from this position.
Even as I now began to press into Indian territory, capturing Karachi and burning down Bangalore/Lahore, Baghdad completed the United Nations, triggering the first election:
It was no coincidence that the UN finished when it did; I actually completed all but one turn's production on it, then sat and waited for about five turns. I was making sure that Cathy and I combined had 50% of the world's population to guarantee control of the Secretary-General. (I had to be careful that the eastern AIs plus Mansa wouldn't have enough votes to win. If they were to vote in something like Universal Suffrage civic, it would destroy my war effort.)
Needless to say, I was overly conservative here and easily dominated the vote. I actually had more votes by myself than the eastern civs combined! (610 to 466) Alexander, who had long been inactive on the global front, even returned to make a valuable contribution here. A quick check of the math revealed that I had 61.0% of the votes. If I could capture or burn down a few more cities, while preserving Alex's vote for me, I could wrap this game up in just four more turns. Forward the tanks!
Of course that didn't mean being reckless. Here was the fortress city I set up in the east, to go along with Bukhara in the west:
With a strong presence at Merw, nothing can slip past and threaten the lightly-defended German cities behind it. Now that I had taken the time to secure my recent gains, it was time to charge forward once more. Onward to Delhi!
Ah, once again the city is returned to the green Arabian banners. Much better than that nasty purple stuff. Although I knew that FDR and Napoleon still had more forces back in reserve, they apparently decided to leave Gandhi out to dry here. I was happy to oblige, and carved a path of destruction across the heartland of India.
What is the definition of "overkill"?
Go ask the poor saps in Bombay.
Even as my tanks tore out Gandhi's throat on the mainland, I was ripping his island colonies a new one as well. First I burned Punjab to the ground (1925), and then grabbed the heavily-defended prize of Jaipur:
This was noteworthy mostly because I had to unload the tanks off the ships. There were about a dozen defenders in this city, but with the city defenses down and the tanks able to blitz, it was still taken without casualties
And while we're on the subject of offshore action, I should mention that I did get the former barb city of Carib back. But it wasn't me who took the city - Cathy actually landed some tanks and did the job! Woo, way to go, girl! 
Of course, I had units on transports about to land and do the job myself, but it was nice to see her making a contribution too.
Once I had taken Bombay, Indus, and Calcutta in the heart of India's equatorial jungles, there was a huge expanse of open territory that I knew would be difficult to defend:
Well, with a combat settler and a Great Artist on hand, I invented myself some protection against AI raiders:
After I found another defensive city in the west (settler en route), I will have strong cultural protection yet again from AI counterattacks.
In the previous four turns I had taken out virtually the entire Indian civilization. With a UN vote due next turn in 1928, I had the potential to end the game right here and now. It would all depend on whether Alex would stand by his Hindu pals or exhibit the usual AI cluelessness. Let's find out.
