The involvement of Lars Porsena (+Horatius Cocles)
the Tarquins approached Lars Porsena, king of Clusium, for help. Clusium declared war on Rome.
Porsena took control of the Janiculum Hill.
3 men volunteered to defend the bridge into Rome, including Horatius Cocles, a distant relative of the Horatii triplets from Hostilius' reign.
once the last Roman soldier crossed the bridge, they cut it away to stop the Tarquins getting into Rome.
Cocles swam the river under heavy enemy fire, supposedly getting impaled for his hard work??