Rank Vs File

[Ciaran]

It depends on the unit, I´d say. For instance, phalanxes more than four or six (depending on the weapon length) waste potential. Cavalry should be deployed two to maximum three lines deep, to get more men smashing into the target and, with a bit of luck, some of then wrapping around the flanks.
Swords should be in two to three lines, too, for much the same reasons. Archers should be in deep blocks, since unlike MTW they don´t get accuracy penalties any more and the deeper the archers are deployed the more archer units you can place behind a given melee frontline.
Yes, thinner formations are more vulnerable to charges, but - and that´s the important part in my opinion - you usually don´t fight a one-on-one battle but you combine troops. So you´ll want to keep your swords out of the horses´ way, let those lazy guys who need to be carried into battle run into a thicket of sharp points.

[Attalus]

Interesting replies, my thanks!

Does anyone know if the formations still receive the depth bonuses as per MTW?

That is, spearmen deployed in the rear rank can support the front rank (in 4 files deep) therefore get a support bonus?

Does it actually make a difference?

I routinely use the republic legion formations:

Hastati H H H H H
Principes P P P P
Triarii T T T T T

With cavalry at the wings (depending on the lay of the land of course) and the odd occassional archer/artillery unit.

I find that I can stretch my ranks right out too 2 deep and still withstand a frontal cavalry charge, then march my principes right into the Hastati lines and repel the cavaly or rout THEM.

I would hate to think that the RTW does not actually take the mass and weight of deeply packed ranks into account.

[Ciaran]

Does anyone know if the formations still receive the depth bonuses as per MTW?

That is, spearmen deployed in the rear rank can support the front rank (in 4 files deep) therefore get a support bonus?

Does it actually make a difference?

No, they don´t. At least not spearmen like the Triarii. If you´re looking for the equivalent of the MTW spears and pikes in RTW, the phalanxes are it, at least as far as the handling in concerned (before the history freaks here crucify me). Strictly speaking, I don´t think they get rank boni, it´s just that due to the phalanx formation the cavalry runs into a true thicket of sharp points and the phalanx unit (as most other spears) do get anti-horse boni.
The spears are best used like the MTW polearms, don´t receive a charge with them (though doing so from 1.3 on reflects some of the cav´s charge bonus back onto them) but charge them yourself into the cavalry.
At least, that´s the condensed wisdom of the Frog Goddess as written in Her game guides.

[lars573]

I always use a standard pattern for attack or defense. I also use the default depth it provides all the rank you need. I also use light cavalry/infantry on flanks to keep threats away.

Republican
Velites=V
Hastati=H
Princepes=P
Triari=T
Archers=A
Equites=E
General=G
Special=(siege engine arcani gladiator merc heavy cav)

V V
EHHHHE
PPPP
TTTT
AGSA

Imperial (early)
Legionary cohort=M
First cohort=F
Auxilia spears=L
Archers=A
Auxilia cavalry=C
Roman Cavalry=E
Legionary cavalry=K
General=G
Special unit (siege engine arcani gladiator)=S
C
LMMMMFL
EMMMMME
AGSA K

Imperial (late west field)
Comiteneses cohort=C
Comiteneses first cohort=F
Fedeorati infantry=B
Fedeorati cavalry=L
Equites Saggitarii=M
Archers=A
Sarmatian auxilia=H
General=G
Special (siege weapon, Praeventores, priest, cart ballista)=S

M M
BCCCCCCCFB
LHA GS AHL

Imperial (late east field)
Comiteneses cohort=C
Comiteneses first cohort=F
Archers=A
General=G
Special (siege weapon, priest, cart ballista)=S
Hippo toxotai=H
Equites auxilia=E
Equites cataphractii/clibinarii=K
H H
ECCCCCCCFE
E A GS A E
KK
Imperial (late west palantina)
General=G
Plumbataii=C
Auxilia palantina=L
Buccelarii=A
Equites saggitarii=M
Fedeorati cavalry=W
Scholae palantina=K
Special (siege weapon, priest, cart ballista)=S

M M
WCCCLLLLCCCW
A GS A
KK

Imperial (late east palantina)
General=G
Plumbataii=C
Legio lancerarii=L
Eastern archers=A
Hippo toxotai=M
Equites auxilia=W
Scholae palantina=K
Special (siege weapon, priest, cart ballista)=S

M M
W LLLL W
CCCCCC
AGSA KK

Now in most of these cases even heavy cavalry will only just push through 1 line of my armies. With phalanx/shield wall armies it is even less penetration of the line. Provided the phalanx/shield wall is prepared of course.