I have been watching the tourney matches lately just like I did with ASM's tourney last year and I noticed that something similar is happening now as happened last year. Last year the complaint was "cataphracts are overpowered" and right now its "heavy infantry (esp. post-Marian Roman) in guard mode are overpowered. Now one might consider that these are near opposite, last year most people quit playing Romans, because the cataphracts were mowing the infantry hordes down. No one cared much about Romans in guard mode, just pin them with phalanx, kill Roman cavalry, ride the legion down with cataphracts for the win. So I just wanted to lay down my understanding of the basics in EB for those who tend to complain before they raise their level of play.
1. Infantry line vs line, if both are similar in strength and size, the defender in guard mode will always win when the attacker becomes exhausted and loses morale. This even includes pike phalanxes on the attack, they will generally tire without doing much damage to the defender, and then are ultra vulnerable to flank and rear attack.
2. Numbers: Line vs line if one line is longer than the other it can turn the unguarded flank/surround the opponent and slowly route down the line. This is why it is important to have reasonably large numbers and as Napoleon I said, "god is on the side of the big battalions."
3. Elites: Get over it. Non-Roman elite infantry cost a lot of money and have low numbers. Spartans, Solduros, Hypaspists, German nobles, Dacian noble infantry are nice to look at, but risky to use, since they require much $$$ and occupy too little space. If a player uses Spartans or Hypaspists or Solduros (elite infantry) in MP and wins, it is because of better strategy, micro, and cavalry dominance, the Spartans did nothing that Thorakitai hoplitai or Helvetian phalanx (read high quality superior infantry) could not have done just as well and for less cost. Watch the top players, and you will see that most are winning with big battalions of common or superior troops because too many elites = small lines = you get enveloped at the flank and speared in the back.
3. Infantry with special effects, such as gaesatae fear, or Carnute druids, wargozes, etc. should be used sparingly with an eye to their increased cost, since everyone goes down when speared in the back.
4. Javelin shower: javelins are best shot in the opponents' flank or back. Commonly when lines approach one another, people leave autofire on, and exchange frontal javelin volleys. When both lines are well armored and have lvl3 or greater shields, as for example Roman legionaries vs. phalanx line, or Romans vs. Thorakitai/neitos, the result is little damage on both sides. This is a waste of javelins. On the flank it is often better to turn autofire off and save javelins for a shot in the flank or back, which can cause an instant route, than it is to leave autofire on and kill 6 or 8 opponents in a full volley. A full javelin volley can also do good damage to enemy cavalry, which can help tip the cavalry balance in one's favor.
5. Elite cavalry: cataphracts and hetairoi are very powerful when used well. But some elite cavalry like Remi mairepos are overpriced and a waste of time. Some elites entail little more than a boost to morale and a slight boost to defense skill, over their superior versions (e.g. Brihentin vs. Remi Mairepos). In highly competitive environments such as MP, it is better to spend money on high quality superior infantry, spending 30% or 40% more on cavalry to get that cool looking elite with one higher attack and defense skill will help to ensure your defeat against a more value conscious competitor. (remember mOre means better, and god is on the side of the big battalions).
6.Turning the flank. Frederick the Great said that the purpose of war has always been to turn the enemy's flank and utterly route them with your cavalry. This is basically the case in EB. In an infantry fight line vs. line, assuming lines of similar mnai cost and similar length, the line fighting in defensive mode will win once the attacker becomes exhausted and loses morale. Once they lose morale they are easily routed by cavalry charge to the back, skirmisher fire to the back, spear volley to the back, horse archery to the back, you get the picture EB is all about shooting and spearing people in the back.
That said, in my opinion the mark of skilled play in EB is about skilled micromanagement in an effort to turn an opponents flank and individually and sequentially route the opponents troops. Towards this end, traditionally in real war, as well as in EB, cavalry are the standard arm of choice. In EB, if one guy attacks in line and the other guy holds line in guard mode, it is generally an auto-win for the defender. Just sit back and wait for his infantry to become exhausted. Skilled players don't commit to combat in line at all, or they attack in line while at the same time outmaneuvering the flank. If this happens (attack in line and flank at the same time), it usually comes down to a winner take all collision at the flank. These collisions are the real crux of EB, and this is where one's extra money should be spent. With horse archers it might be possible to shoot down the opposing cavalry and archery and leave the flank exposed to cav charges with little fight. Otherwise certain troop types, like elephants, gaesatae, cataphracts, AP/high lethality troops like guild warriors/rhomps/swordmasters, and high value infantry like Pedites extraordinarii, Arjos, and Thrakian peltasts can all have strong impact at the decisive collision. And whoever has extra resources to throw at the decisive point and manages his forces more skillfully rightfully gains the right to lance/shoot his opponent in the back and win the battle.
So those are my observations, I would be interested to hear anything other people have to say concerning the basic principles of skilled play in EB. Mainly I think that at a high level of play EB tends to move away from a simple battle in line with guard mode= win, and becomes an evolving attempt to outmaneuver one's opponent, surround, crush individual troops, and initiate chainroutes, and at that point the game can be advanced and I think the number of army systems and strategies that could work would be greater than what I have seen in the tournament play.