The Primary Record
Livy blamed Hannibal.
In Book 21 Chapter 21.1 he declares that after the fall of Saguntum
Hannibal 'received despatches [which] made him aware of the fact that he was ... (in Roman eyes) the cause of the impending war'.
In his account of the Battle of Zama, Livy goes further and makes Hannibal
say explicitly: 'It was I who first began this war against the Roman people'.
Later Roman writers (e.g. Appian)
also blamed Hannibal for starting the war by - they said - crossing Ebro and breaking the Treaty of 226bc. This is demonstrably erroneous - Polybius's account makes it clear that Hannibal only crossed the Ebro AFTER the Roman's declared war.
Polybius (Book 3, Chapter 6)
criticises these historians, declaring that there were three causes of the war - the 'wrath of Hamilcar', the Roman annexation of Sardinia, and Carthaginian expansion in Spain. But he has confused historians ever since by
agreeing that Saguntum and crossing the Ebro were the ἀρχάς (archas
- beginnings/ origins/ foundations) of the war; he did not criticise the
other historians because their facts were chronologically wrong, but on the academic quibble that
Saguntum and the Ebro were the occasion, not the causes, of the war.
The Secondary Interpretations
Many secondary historians have written about this - one book notes 34 significant contributions since 1896!
The problem of Polybius
So what is going on about the Ebro Treaty? Why did all the ancient writers - including Polybius - suggest that Hannibal
occasioned the war by breaking the Ebro Treaty ... when he didn't?
The generally-accepted solution to this was advanced by German historian Eduard Meyer, who argued (1913) that Polybius was so beguiled by Roman traditions that Hannibal caused the war by crossing the Ebro, that he didn’t notice (or glossed over) that – by his chronology – war broke out before Hannibal crossed the Ebro.
Other theories to explain this – e.g. that of French historian Jerome Carcopino, who suggested (1953) that the River Iber in the 231bc treaty was the Jucar, not the Ebro; and German historian
Wilhelm Hoffmann, who suggested (1951) that the ultimatum followed the crossing of the river and that Polybius got his chronology wrong – are not generally taken seriously.
Who was to blame for the war?
Many historians have blamed
Carthage, seeing Carthaginian expansion in Spain as an anti-Roman policy and the Roman declaration of war as ‘essentially defensive’.
North-East scholar R Malcolm Errington (1970) argued that the Romans only got involved after pressure from/they were invited by Saguntum and Massilia, fearful of the growing power of Carthage.
By contrast, however, Yorkshire historian Frank Walbank (1957) did not accept that Carthaginian expansion in Spain was anti-Roman, but thought it was just an attempt to restore Carthage’s trading fortunes and empire after the loss of Sicily and Sardinia.
William V Harris (1979; he was Professor of History at Columbia University, New York) argued that the nature of the Roman empire meant that it had to continually and aggressively expand. These theories would tend to
put the blame on Rome.
(Remember that I am a History teacher, not a Ancient History professor!)
You can read my full reasoning on my blog-post
here, but I - although I am prepared to see the war
essentially as ‘an imperial, economic and cultural death-struggle between two
competing empires’ - think that the war was the result of a nervous Rome seizing
upon the Saguntum Outrage as an opportunity to ‘pick a fight’ with the growing
power of Hannibal.