with the end that actual defense/fighting was ultimately outsourced to foederati who naturally disposed of the last emperor.
https://en.wikipedia.org/wiki/Foederati#5th_century
"By the 5th century, lacking the wealth needed to pay and train a professional army, Western Roman military strength was almost entirely reliant on foederati units. [...] and the foederati would deliver the fatal blow to the dying nominal Western Roman Empire in 476, when their commander Odoacer deposed the usurper Western Emperor, Romulus Augustulus"