I recently got to thinking about RTW again, and decided to write up a short piece on the Seleukid Empire, one of the diodachoi or Successor States left behind after the death of Alexander III and the dissolution of his empire. Their army has a unique combination of Greek, Roman, and Middle Eastern influences that make it one of the strongest and most flexible forces in the game (their units were detailed in my earlier entry about the Greeks. Scroll down a wee bit).The Seleukids also control rich lands in Syria and Mesopotamia, with the wealth of Greece and Egypt easily within their reach. However, they, like the Greek Cities, start out with vulnerable, far-flung cities surrounded by many potential enemies. Their cities stretch in almost a straight line from the western coast of Asia Minor all the way to the foot of the Iranian Plateau. They share borders with the Greeks, Armenians, Parthians, Pontians, and Egyptians, as well as a number of independent cities which can quickly change the strategic situation, regardless of who conquers them. Needless to say, the Seleukids must spend much of the early game trying to maintain diplomatic relations between many potential allies and enemies.
However, prospects are good if you can survive the early stages. Ptolemaic Egypt, another Successor State and a historical blood enemy of Seleukia, will attack early and often, but good generalship and aggressive campaigning can gradually push them back to the Nile itself. A sound strategy is to land a small force on Cyprus and force the Egyptians out of Salamis- this deprives Egypt of a secure naval base and nets you considerable overseas trade. From there, your forces can advance almost in a straight line, issuing out of Damascus, marching south into Phoenicia to sieze Sidon, then continuing south to Jerusalem. A sharp turn west brings you to the Nile delta, where your army must cross several narrow, easily defended bridges before reaching Alexandria. This is the most dangerous terrain you'll face in your Egyptian campaign, but hopefully Egypt's armies will have been sufficiently depleted in the battles for Judea and Phoenicia. Once Alexandria falls, there is little hope for an Egyptian comeback- Thebes and Memphis are only a stone's throw away, and although they are both very large, rich cities, they can't hope to field enough men to match whatever experienced troops and officers you should have at this point.
So, what about the actual nuts-and-bolts of defeating the Egyptians; how does their army operate, what are its strengths and weaknesses? How do their troops compare to the Seleukids? Although the Egyptian troops are extremely Egyptian-looking, in form and function they very closely resemble the Carthaginian or even Greek armies. Their most common infantry, the Nile Spearman, is a phalanx unit, and a competent one. Like the Carthies and Greeks, they carry fairly long spears, with about three points extending out in front of their formation. However, the spear carried by your phalangites, the Macedonian-style sarissa, is much longer, with up to five spearpoints projecting ahead of your ranks. However, unlike Greek or Carthaginian hoplites, who make up for their shorter spears with heavier armor, the Nile Spearman is not particularly tough. It may be able to contend with your Levy Pikemen, who are not even a match for Milita Hoplites (or Egypt's Nubian Spearmen, who are identical statistically) on an individual basis, but your Phalanx Pikemen- good infantry by anyone's standards- should eat them for lunch. However, Egypt has another infantry unit which my prove more problematic- the Desert Axeman. These excellent heavy infantrymen are, statistically speaking, more than a match for most of your troops in hand-to-hand fighting. Fortunately for you, you can put five spearpoints between them and your phalangites, so long as they attack from the front. The bad news is, these men, fighting in loose formation on open ground, are substantially faster and more maneuverable than pikemen advancing in close order. They are extremely dangerous to your flanks- guard them well with cavalry.
On the subject of cavalry, yours and the Egyptians are roughly on a par. Early Seleukid cavalry is basically identical to that of the Greeks- you get Greek Cavalry, which are effective lancers, and Militia Cavalry, which are weak in close fighting but can throw javelins while moving. These horsemen are fast, light, and cheap, making them a good counterpart to your ponderous Pikemen. The Egyptians have two light lancer-type units, Nubian Cavalry (slightly weaker than Greek Cavalry) and Nile Cavalry (slightly stronger than Greek Cavalry). These, however, are less common than chariots, the thing that really sets Egyptians apart. Some carry archers,and some carry swordsmen, but both have scythed wheels that are deadly when charging- unless they're charging into pikes. Although charging chariots will sometimes have just enough momentum to breach the spearwall and deal some casualties, they will invariably be destroyed in the process. Chariot archers are also so relatively few in number that they can easily be outshot by foot archers. However, they candevastate whatever non-phalanx infantry you have (missile troops and mercenaries) with their unstoppable charge, and in a battle with cavalry, they will usually be defeated (due to their low defense) but at great cost (due to their ability to mow down many soldiers at once with their scythed wheels). Militia Cavalry are still very effective against them, since they can avoid actually closing with the enemywhile hitting them with javelins, which are very effective at killing their crews. Of course, you can train Chariots of your own- they are less effective than Egyptian ones, however, since they have only a driver, now archers or swordsmen. Theymay be usefulagainst the light infantry of Armenia, Pontus, and Parthia, but against the massed spearmen of Egypt, they're not particularly useful.
In missile troops, the Seleukids probably have the advantage in the early game. The Seleukids can train archers, which are extremely effective against the kind of massed, lightly-armored spearmen you'll probably face early and often, and can also train Peltasts, javelin-throwers who, despite short range and low ammunition, make excellent close-in support for your slow-moving phalanxes. The Egyptians can also train archers, but instead of peltasts, they train slingers. Slingers have long range and lots of ammunition, but are less lethal than archers and, because they fire along a flat trajectory rather than an arc, can only provide support before the melee infantry engage. Needless to say, you'll probably be seeing a lot more archers than slingers during your campaigns. If you take your time, you may encounter Pharaoh's Bowmen, which besides being extremely deadly at long range are also well-armored and competent at hand-to-hand fighting. These troops are deadly against your own archers and especially your slow-moving, densely-packed phalangites. It's best to try and finish the Ptolemies off before they can get such superb troops.
So, basically, your Pikeman units will be very effective against the Egyptian infantry and chariots, so long as you make good use of combined-arms tactics, as Alexander the Great did.Use your phalanxes as a strong base of maneuver, protecting your missile troops from enemy horsemen and chariots and holding the enemy infantry in place for your fast, light horsemen. Keep winning battles and taking cities, and you should be able to gradually grind the Egyptians to dust. With their rich territories added to your kingdom, you have a strong, secure base and, due to your many victories, a large and experienced army under a famous commander. The good news is that, with this new strength, it should be easy to seize the rest of Asia. Pontus and Armenia are both small kingdoms with only 2 cities initially, and although the Parthians own an additional city on the northern coast of the Caspian Sea, they also have only 2 starting cities in Asia. All three of these factions rely mainly on Hillmen and Eastern Infantry, unarmored soldiers with short spears and wicker shields. Your phalanxes will wade through them. These three kingdoms will often make good use of cavalry as well though; employing missile cavalry early on and later developing superb heavy cavalry, but you should be able to eliminate both before any of their cities are sophisticated enough to produce high-tier troops. In response to the missile cavalry that you will doubtless encounter, it's probably best to have your own foot archers engage them at range, with your own cavalry ready to repel a charge. Sending cavalry of your own to chase them down is sometimes worthwhile, but often just leads your horsemen away from the real battle, tiring them and reducing their effectiveness. The Pontic Heavy Cavalry, mounted javelin men, are actually quite tough for low-tier cavalry, and pursuing them can sometimes result in a bloody melee. Basically, fight defensively with your archers and pikemen and hold your cavalry in reserve, and you may even defeat them before you conquer Egypt.
With all the land from the Caucasus to the Nile delta now under your control, you have three main options- you can march through the wastes of Libya to reach the rich cities of West Africa, you can cross the Hellespont to subjugate Greece, Thrace, and Macedon, or you can march north via the Caucasus mountains, to mop up the last of the Parthians and conquer Scythia. The third is the least cost-effective. The Seleukid army is poorly suited to warfare against horse archers on the open plains of Ukraine and Russia, and the cities of the region are small and unsophisticated (read: not worth conquering). Although West Africa is a rich prize, a long march through the open deserts between Thebes and Thapsus means wasted time, and a diversion from the richer and more immediate prizes of the southern Balkans. With the collossaltrade income and large powerbase that Greece and Macedon will give you, your kingdom will be prepared to take on the Romans- in fact, you'll probably run into the Roman Scipii during your Greek campaign.
Against the Romans, your best bet is to try to defeat them through superior combined-arms tactics. That is to say, don't rely too heavily on infantry. Use your high-tier heavy cavalry, the Cataphracts and Companions, and make good use of your Silver Shield Legionaries, which make for a good link between your phalangites and horsemen and may even be your infantry-of-the-line in some armies. Don't forget Elephants, either. Your elephants and cavalry are the biggest advantage you'll have over the Romans,but your phalanx is both a blessing and a curse- it gives your infantry a chance to beat superior forces in head-on combat, but leaves them miserably vulnerable to enemy flanking attacks and missile fire. Just fight the good fight and your forces should be parading through Rome in no time.

_veDnoR