Iron Technology, Climate and Warfare

Basis of Iron Age climate records.

Iron Age in context.
See F. McDermott et al 2001 in the journal Science. Vol. 294. no. 5545, pp. 1328 - 1331

Climate during the Iron Age
Based on this data, temperature gradients during the Iron Age are within reasonable bands compared to today.
There is no evidence to suggests a ‘cold snap’ or other catastrophic event, despite a relatively narrow tree ring event at 207 BC and volcanic acid layers in ice cores at 210+/-30 BC. Tree rings and layers in the ice core provide data that is an approximate of the climate at that time.
Comparison of two pollen sequences from the midlands (Corlea, Longford; Derryville, Tipperary).
Does this suggest a climatic problem around 207 BC?
Derryville: Pollen Diagram
Climate information and archaeological data
Grey bands equate to dry episodes.
Graphs indicate growth of bog oaks (line) and lake oaks (black), with peaks reflecting drier conditions.
Turney et al. 2006 Journal of Archaeological Science Vol 33, 34-38
Iron Age Ireland
Iron Technology
Chemical symbol for iron is Fe
Naturally occuring mostly as oxides or carbonates:
Iron ore
Hematite
Magnetite
Naturally occurs in many geological strata, chalk, lakes, bogs:
Earth's crust is 5% iron (comapre 50 parts per million of copper and only 3 ppm tin)
Iron ore more plentiful on the surface than copper
Main drawback – more difficult to process, requiring higher temperatures.

Iron Ores: even distribution
Iron Technology
The production process produces a bloom containing iron, which is forged and hammered so that it is purged of as much waste material as possible, which congeals to form lumps of metallic rock known as slag (top left).
The bloom is then cleaned and by heating and quenching it it can be hammered out into ingots (bottom right) or shaped to form objects.
What traces would this leave?
Objects?
Furnaces?
Slag?
Other?
Ore Preparation
Crushing Ore: Bedrock Mortars
Bullauns?
Heating Ore: Charcoal
Iron technology: adding Oxygen
Producing iron ore requires a furnace (powered by charcoal) to achieve the required temperatures.
Basically, when you have crushed the ore, you then heat it to 1538°C at which point iron melts.
Oxygen
Smelting Ore: Furnaces
Shaft Furnaces
Furnaces do leave some traces that can be recovered during excavation.
Early Iron working in Ireland
Smithing hearth at Rossan 6, dated to 820-780 BC
Bloom smithing/iron working hearth at Griffinstown 3, dated to 420-360 BC
Bowl furnace at Johnstown 3, Meath, dated to 420-360 BC
Bowl furnace at Kinnegad 2, dated to 400-340 BC
Smithing hearth at Rossan 6, dated to 370-50 BC
Bowl furnace at Hardwood 3, dated 380-60 BC
More information on these sites at www.nra.ie/Archaeology/
Primary Smithing
Secondary Smithing
Smelting and Smithing Slags
Hammerscale
Hartshill in England produced evidence suggesting the presence of iron working as early as the 10th BC.
It was in the form of tiny fragments of hammerscale, some less than a millimetre in size (shown in the image on the right), rather than furnaces or slag.
Hartshill, West Berkshire, England
Iron Age Iron Working in Ireland

Sites with clear evidence of Iron Age iron working are relatively rare in Ireland although some examples, such as Rath na Riogh, at Tara, are known.


Blacksmiths
The complex and dangerous process of transforming “stone” to metal provides a special position for blacksmiths in many societies
There may be ceremonies and rituals associated with the process
Blacksmiths are often seen as figures with supernatural powers

Early Warriors
Hochdorf
La Frondelle: the goddess Epona
Chariots
Defended Hilltop sites – Hillforts
Most perceptions of Celtic warfare are driven by Classical accounts, many of which are considerably later than the earliest sites.
Murus Gallicus, according to Caesar
Heuneburg

Pfostenschlitzmauer
Manching
Celtic Migrations: timeline
Allia and Rome
Celts in War
Pergamon

The Romans faced by the Celts
One days march; 15-20 miles. Overrall length of column 22.5 miles
Average speed; 3 miles per hour
Total army makeup- based on a six legion army;
Legionary troops;30,000
Ancillary troops;3,500
Gallic Cavalry Wing;4,000
Roman cavalry;720
Servants;6,500
Horses;4,720
Total mules;10,000
The Romans faced by the Celts
Legion Staff- ancillary troops, clerks, technicians, specialists, reserve tentage, cavalry equipment, field hospital, medical staff, veterinary staff, engineering stores, workshops.
Caesar maintained that at any one time there were between 300-500 sick
Food: Daily requirement 3lbs per day per man. Each man carried 10 days ration
Artillery included: siege engines, Ballistae, Caterpults and Onagers
Caesar against the Helvetii (58 BC)
Celeritas and Clemencia (Caesar)
“ The battle ended, that he might be able to come up with the remaining forces, he procures a bridge to be made across the Saone. The Helvetii, confused by his sudden arrival, when they had found that he had effected in one day what they themselves had difficulty in accomplishing in twenty….send ambassadors to him.”


“ He ordered the Helvetii to return to their territories from which they had come and as there was nothing at home whereby they might support their hunger, he commanded the Allobroges to let them have a plentiful supply of corn.”
Keeping a Tally
“The sum of all amounted to …368,000.When the census of those who returned home was taken, as Caesar commanded the number was found to be 110,000.” Book 1 (Bello Gallico)

“ On the basis of Caesar’s report, the Senate granted him a Supplicatio of fifteen days.. The Senate was paying him respect for the Conquest of the whole of Gaul. At the same time, it was indirectly confirming his command and the legitimacy of his wars. It was honouring him in such a way that the transgression of 59 were bound to pale. Its decision, thus represented a quite extraordinary success for Caesar, however little it meant in material terms”. C Meier



Caesar against the Venetii
The Roman naval tactics consisted mainly in either propelling a vessel with great force against a rival and crushing the side, or in catching hold of the hostile craft with hooks, pulling alongside, springing over on it, and settling the conflict with a hand-to-hand fight. In the sea-fight with the Veneti, who had only sailing vessels, the Roman sailors crippled the enemy's ships by cutting down the sail-yards
Delegation, Innovation and Recognition
“ One thing provided by our men was of great service..sharp hooks inserted into and fastened upon poles….When the ropes were caught by them and pulled…the yards necessarily fell down, so that all hope of the Gallic vessels of the Gallic vessels depending on their sails was taken from them”


“The rest of the contest depended on courage; in which our men decidedly had the advantage; and the more so, because the whole action was carried on in the sight of Caesar and the entire army; so that no act, a little more valiant than ordinary, could pass unobserved”.
Defensive Works at Bourges
The Battle at Gergovia
A Rare Defeat?
In 52 BC Gergovia was the stronghold of Vercingetorix. It is famous for being the only place where Julius Caesar was defeated in the Gaulish wars. After conquering Avaricum, Caesar took six legions onward to Gergovia where he attempted a siege. He was outnumbered when the Aedui, formerly the Romans' allies, surprised Caesar by joining with Vercingetorix. As Caesar's army marched towards the great Arverni hillfort of Gergovie, Vercingetorix was setting out with his own army on the other side of the river Allier, breaking every bridge along the way to be sure the Romans could not cross over. Caesar, however, hid two legions in the woods. After Vercingetorix moved on, they rebuilt one of the bridges and went on to attempt the siege of Gergovia. The assault failed. Over 700 soldiers and 40 centurions were lost in the battle before Caesar drew back. Encouraged by this victory, the Gauls persisted in their revolt until their final defeat at Alesia.
The Battle of Alesia

Intelligence and leadership.
“ As the action was carried on in sight of all, neither a brave nor cowardly act could be concealed; both the desire of praise and the fear of ignominy, urged on each party to valor….Caesar sends at first young Brutus and afterwards Caius Fabius, his liutenant…….His arrival being known from the colour of his robe….the enemy joined battle.”
“Caesar on learning these proceedings from the deserters and captives, adopted the following system of fortification”.
Archaeological evidence at Alesia
Orange, Vaucluse
Caesar’s Siege Works at Alesia
Dun Aonghusa, Inis Mór, Aran Islands