ISSUE 176 : Jul/Aug - 2008 - Australian Defence Force Journal

Disorder unmanaged: The Milvian Bridge and PQ-17
Military history is replete with examples of rampant disorder. I will consider two here which give
quite different insights into what disorder in the battlespace might mean and the relationship
to command and control.
The Battle of the Milvian Bridge took place on 28 October 312 AD between rival Roman
armies. On the one side, forces led by Constantine, co-emperor of Britain and Gaul, invaded
Italy through the Alps, sweeping across the cities of the Po Valley and then descending down
the Via Flaminia toward Rome. On the other side, Maxentius, co-emperor of Italy and North
Africa, was expecting Constantine and had the northern entry into the city of Rome prepared
with ambushes in the land between the city walls and the Tiber River, as well as a pontoon
bridge running parallel to the Milvian Bridge, the means of passage from the north of Rome’s
watercourse. Maxentius’ strategy was sound: wait for Constantine to cross and then annihilate
his forces between the city walls and the river or drive the panicked force into the river
itself. However, in an extraordinary act of hubris, Maxentius led his army over the river and
attacked Constantine in the hill country at the confluence of the Via Cassia and Via Flaminia,
a place called to this day Saxa Rubra. Constantine’s cavalry line prevailed, driving back horses
and men in a wild panic toward the Tiber River. Maxentius’ trap had sprung back on himself.
His army rushed toward the Milvian Bridge, the pontoon bridge having already been pulled
down—an act of sabotage perhaps? The mass of men and horses on the wooden Milvian
Bridge overwhelmed the structure: the timbers collapsed and man and horse fell headlong
into the river, including Maxentius himself who drowned dragged under the turbulent waters
by the weight of his armour.
An organised army, which had the benefit of military doctrine on the conduct of a retreat
(as documented by Flavius Vegetius Renatus, 2 for example) had become a rabble. The word
disorder certainly comes to mind in this context as well as irreversible, at least after the collapse
of Maxentius’ infantry lines. Both of these words are interlinked in the physics concept of
entropy. The other dimension to this engagement was the absence of a command and control
system. This coincidence, I argue, is not a chance event. Undoubtedly, military practitioners
can cite many such cases up to modern times where the absence of active command and
control arrangements had led to manifest disorder in the battlespace and an irreversible path
to military disaster.
However, lest the sheer violence of this engagement mislead us, I consider now a rather
contrasting case: the fate of Arctic Convoy PQ-17 in WWII. Consisting of 39 merchant ships
and an escort of corvettes and destroyers, PQ-17 set sail on 3 July 1942 from Iceland bound,
initially, for Murmansk. The convoy was shadowed by a cruiser squadron which, however, had
a second purpose: to engage with the German warship Tirpitz which had spent much of the
war hiding in Norwegian fjords. Similarly, the Allied Home Fleet scouted to the north-west
of Norway but would only cover the convoy up to a line of longitude extending from North
Cape. An initial attack by torpedo bombers at 2030hrs on 4 July coincided with fears the Tirpitz
had left her berth for open seas. Admiral Sir Dudley Pound, the First Sea Lord, issued a fateful
order that the convoy should disperse while Commander Jack Broome of the escort group
detached his destroyers from the merchant ships in order to join the battle group for action
with the Tirpitz. In fact, the Tirpitz had merely sought another Norwegian berth. But the genie
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