This is a very good basic introduction to the subject - and to be honest, as there isn't that much information to begin with, and greater depth would involve listing small bits of archaeological evidence and going into detailed academic arguments over the interpretation thereof.
The Contents are:
P04: Introduction
P07: Chronology of major events
P09: Italy before Rome
.Villanovans; Etruscans; Latins; Sabines; Oscans; Greeks
P18: Early Roman Warfare
.Clan warfare; City-state warfare
P27: Levying
.Clan gathering; Citizen muster
P33: Equipment and Appearance
.Spear; Sword; Shield; Citizen phalanx
P44: Belief and Belonging
.Gods of crops and war; Group identity
P49: On Campaign
.Raid and ambuscade; Pitched battle
P62: Glossary; Bibliography
P64: Index
The author describes the evolution of the Roman warrior from a brigand and cattle-raider, to a member of a tribal war-band (still interested in brigandage and cattle raiding) to membership of a citizen-phalanx, examining cultural influences from the neighbouring tribes, and the evolution of weaponry and armour, as well as the evolution of the cultural / civic milieu in which the warrior existed. The next stage of Roman military evolution / development would be the conversion of the warrior to soldier (a major cultural change).
The colour plates are:
A: Clan chieftain - "They were resplendent in shining helmets, pectorals and greaves, which were fashioned from beaten bronze often beautified with embossing". As well as showing a clan chieftain in full panoply, there are detailed illustrations of his armour, plus a range of swords and helmets.
B: Clan warrior - "...these Roman warriors of fewer means, the military backbone of warbands, were without armour and almost certainly armed with a shield for protection and a spear for thrusting, with perhaps hand weapons such as a dagger or axe for close-quarters battle". As well as a figure of the clan warrior, there are detailed illustrations of spear and axe-heads, and a deconstructed helmet.
C: Citizen-soldier, Class 1 - "Servian class 1 citizen-soldiers fought essentially with hoplite panoply". Here we see the hoplite, with extra details of the inside of the shield, sword and greaves.
D: Citizen-soldier, Class 3 - "The less well-off citizen would have had nothing so elaborate as the bronze or linen corselet that wealthier citizens wore." The figure here has spear, shield (scutum), helmet, sword, and small `pectoral' bronze breastplate. Also illustrated are a selection of helmets and breastplates.
E: Raid, Sabine settlement, c.750 BC - "Here we witness one such attack on a Sabine hilltop hamlet. Its men have fallen defending hearth and home, and the Roman raiders are now consigning the settlement to a bloody plunder, killing its elderly, abducting and enslaving its womenfolk and dragging off all its portable wealth". Some clan warriors herding the womenfolk, while in the background there are other warriors torching the huts, with various casualties lying about.
F: Victory, Lake Regillus, 499 BC - "Here we join the battle at the moment the equites, having jumped from their horses, join the depleted ranks of their weary comrades." Mainly heads and shields shoving in a melee, with more detailed figures in the background.
G: Surrender, The Caudine Forks, 321 BC - here we see "Roman soldiers, who were cld only in their tunics... crouch down" to pass under the frame of spears forming the yoke, "a very Italic symbol of defeat", with lots of armoured Samnites in the background in good detail.
H: Defeat, The Allia, 390 BC - "It was on the banks of the Allia...that the Senones utterly crushed the army sent to repel them". This is another big melee, this time with the hoplite Romans in combat with Gauls.
This is a good selection of plates, showing the warriors and their activities.
Further reading:
Roman Battle Tactics 390110 BC (Elite)
Early Roman Armies (Men-at-arms)
Roman Centurions 75331 BC (Men-at-arms)
Mediterranean Anarchy, Interstate War, and the Rise of Rome (Hellenistic Culture and Society)
Andrea Palladio and the Architecture of Battle with the Unpublished Edition of Polybius' Histories
New Perspectives on Ancient Warfare (History of Warfare (Brill))