Tied up by Alaric’s invasion, the Western emperor Honorius felt compelled to recognize the Gallic usurper Constantine III in late 408. However, Constantine’s fortunes took a sudden turn for the worse just months later, when his general Gerontius revolted with much of his army in Hispaniae and proclaimed a rival emperor, Maximus.
In late 408 Constantine III sent an embassy to Honorius in Ravenna, asking that he be accepted as co-emperor. His hands already full with Alaric’s Goths, Honorius relented and sent Constantine a purple robe and imperial regalia in formal acknowledgement of his accession. However, the move was never recognized in the East, where Theodosius II and his government continued to consider Constantine a usurper.in wikipedia
In January 409 an embassy from Rome arrived in Ravenna, asking the Western Roman emperor Honorius to accept Alaric’s terms and agree to an exchange of hostages. However, Honorius, under the influence of his magister officiorum Olympius, rejected both this embassy and another one led by Pope Innocent I a few months later, opting instead for continued hostility with the Goths. To this end, Honorius sent for five regiments (up to 6,000 men) from Dalmatia to reinforce Rome, but this was intercepted by Alaric as it passed through Tuscany and only its leader Valens, the treasurer Attalus, and 100 men made it into the city.in wikipedia
While Pope Innocent I’s embassy from Rome was in Ravenna in early 409, news reached Honorius that Alaric’s brother-in-law Athaulf had just crossed the Julian Alps into Italy with another Gothic army from Pannonia. Honorius’ magister officiorum Olympius quickly assembled a force including 300 Huns and intercepted the invaders at Pisa, but, despite allegedly killing 1,100 Goths for the loss of just 17, was unable to stop Athaulf from joining Alaric in Tuscany. This failure ended the career of Olympius, whose seven-month primacy had seen nothing but disaster, and soon afterwards he fled to Dalmatia.in wikipedia
In spring 409 Constantine III dispatched his son Constans—who he had by around this time elevated to co-augustus—back to Hispaniae with a general named Justus. Perhaps concerned that he was being replaced, the magister militum Gerontius, who was still in Spain, revolted and proclaimed his domesticus Maximus as emperor at Tarraco. Supported by most of the army, if not all the Spanish provinces, Gerontius quickly convinced Constans to return to Gaul.in wikipedia