Ancient Romans for centuries relished a much earlier story of a battle on a different bridge. It all began when Ancus Martius built the famous "wooden bridge", the first bridge across the Tiber. Ancus was the fourth of Rome's seven kings, and he reigned from 642 to 617 BC. His three great accomplishments, according to legend, were the founding of the port city of Ostia, the building of Rome's first prison (the Mamertine), and the wooden bridge. The bridge was called the Pons Sublicius because, according to ancient sources, "sublices" meant wood in one of the local dialects -- "pons" is Latin for bridge.
This, of course, was long before the first flood-control embankments were built on the Tiber, so the bridge had a raised approach on the Rome side to make it useable when the river was high. The bridge was located about 150 meters south of the present Palatine Bridge and ran straight west from about where today stands the "mouth of truth" on the porch of S. Maria in Cosmedine church. Development of Trastevere, on the other side of the River at the base of the Janiculum hill, began in earnest.
The bridge may have been a real-estate salesman's dream, but it was also a strategic nightmare. (Warning: Legends ahead!) One terrible morning in the late sixth century (about 509 BC), more than a hundred years after the bridge was built, the Romans woke up to find Etruscan tribes led by Lars Porsena in possession of the Janiculum side of the River. As is often the case under such circumstances, there was general consternation, despair, and cowardice. But a young lieutenant named Horatius Cocles was stationed at the Janiculum end of the bridge with a small detachment of Roman citizen-soldiers. He shamed two young noblemen into staying with him while his men chopped and burned down the bridge behind them. That took a while, and during the chopping and burning Horatius and the other two accounted for a heap of enemies which piled so high in front of them that the huge Etruscan force shrunk from moving forward. At the last minute, Horatius ordered his two companions to retreat while he guarded the bridge and fought on alone. Finally, after the bridge was totally destroyed, he leapt into the Tiber and swam, much wounded, to the Roman side of the river where he received a well deserved hero's welcome. The tale of Horatius was included in Livy's great History of Rome (Ab Urbi Condita) and was repeated endlessly to Roman school children and to new military recruits.
In American Revolutionary times the story of Horatius was used to encourage outnumbered colonists to stand firm against larger English forces. Obvious comparisons were drawn between the Horatius defense and the defense of North Bridge in Concord Massachusetts by a few patriots at the beginning of the Revolution. "Horatius (or Horatio) at the Bridge" thus entered into the US canon of patriotic themes and was the subject of innumerable student essays from then until today -- any graduate of US military schools, the Service Academies, or the Staff or War Colleges can tell the tale, though few will know that the Roman bridge in question was the Pons Sublicius.
PS: When the Sublicius bridge was rebuilt after the Horatius defense, it was not nailed together. Instead, wooden pins and wedges held the timbers in place -- so that it could be quickly disassembled if another enemy approached. Because of the legend, the Pons Sublicius kept its wooden construction long after other stone bridges were built across the Tiber. Only the High Priest (the Pontifex Maximus = Greatest Bridge-Builder) could order any change or repairs to this bridge. In numerous reconstructions, rebuildings, and replacements, it was finally built in stone, and eventually the Pons Aemilius slightly to the north replaced it. Authorities differ over whether the Sublicius and the Aemilius ever coexisted. The last iteration of the Pons Aemilius collapsed in 1598 and has since been called the Ponte Rotto (rotten bridge.) The remains of the Ponte Rotto are just north of the post-Unification (1886) cast-iron Palatine Bridge, which is the current replacement of the Pons Sublicius.
Even in ancient times, the legend of Horatius was doubted. Another legend, peddled by the famous Roman Scaevola family, ascribes the defeat of Lars Porsena to Gaius Mucius. Gaius tried to assassinate Porsena but killed a servant instead. Brought before Porsena, he claimed he was one of 300 noble youths who had sworn to kill Porsena. To demonstrate his fortitude and the truth of his claim, he thrust his right hand into a fire, burning it off. Porsena, both impressed and fearful, sent Gaius Mucius home and withdrew with his army. Thereafter, Gaius Mucius was called "Scaevolus" meaning "lefty".
Internet Links:
Roman Bridges in the Smith Dictionary:
http://www.ukans.edu/history/index/europe/ancient_rome/E/Roman/Texts/secondary/SMIGRA*/Pons.html
Livy's account -- Volume 1, 2.10:
http://etext.lib.virginia.edu/etcbin/toccer-new?id=Liv1His&images=images/modeng&data=/texts/english/modeng/parsed&tag=public&part=70&division=div1
Mccauley (Lays of ancient Rome)
Account with Latin references:
http://www10.geocities.com/Athens/Styx/1790/horatius.html