Second Blockage of Rome by Alaric
King Alaric of the Visigoths, a friend of Flavius Stilicho, tried to push his personal demands on the Western Roman Emperor Honorius, which consisted in the concession of a block of territory 200 miles long by 150 wide between the Danube and the Gulf of Venice (to be held probably on some terms of nominal dependence on the Empire) and the title of commander-in-chief of the Imperial Army.
However, the Emperor refused, against all advice from Stilicho. Alaric thus decided to besiege Rome in order to make pression on Honorius. But thinking he was safe in Ravenna, the Emperor refused any attempt of negotiation from Alaric. So Alaric decided to deal with the Senate instead and elected a rival Emperor, the prefect of the city, Priscus Attalus.
Reconquest of Rome by Stilicho
Alaric brother-in-law, Ataulf, has been left in Rome to control the local population while Alaric was returning north. Using the occasion, Stilicho was allowed by Honorius to take troops and retake Rome. In early May 410, Stilicho and his men were able to siege the city during two weeks, after which Ataulf and his men faced him on the field out of Rome. The battle was a victory for the Romans, although Ataulf and his men were able to escape and return to the safety of Rome. By the end of June, however, Ataulf and Priscus Attalus were killed by the angry population of Rome, after which their head were presented to Stilicho.
Battle of Tarquina
After learning the defeat of his troops in Rome, Alaric returned south in order to sack Rome and defeat Stilicho. Although both men had respect for each other, their was no way to avoid this fight. Alaric was ale to dispose of most forces that stood in his way while he was going toward Rome. During that time, Stilicho assembled what he had left of troops and organized the defence in Tarquina, a small town north of Rome. He also tried to form a militia among the citizens so he could have more troops at his disposal. The battle, which lasted on three days, was a close victory for the Romans achieved with the help of the citizens of Tarquina during the third day.
Following his defeat, Alaric was forced to retreat into northern Italy, Roman troops under Stilicho chased the Visigoths, although only small altercations followed. Alaric though about conquering Ravenna, but the fortified city was too protected for the defeated army of Visigoths, and the pursuit led by Stilicho was still after them.
Alaric escaped Italy with his men without too much fight. Stilicho, who was left with a victorious but weak army, stop chasing the Visigoths after they escaped Italy and focus on rebuilding the defences of the region. Alaric and his men instead conquered Roman Dalmatia in early 411. The Roman forces in garrison were easily defeated, and Stilicho was forced to abandon the region due to his lack of troops. The Visigoths settled there and formed the Visigothic Kingdom, with Alaric as there King.