Pompey, whose success at sea had already induced him to exchange the customary purple cloak of the Roman commander for a dark blue one, "as the adopted son of Neptune," inflicted on Octavian the defeat that the latter had anticipated, but was shortly afterwards himself defeated at Naulochus by Agrippa, whom Octavian, a few years later, after the battle of Actium, honoured with a special dark blue flag[31] as a symbol of his naval superiority. From the account given by Appian of the action off Naulochus it is clear that there was no distinguishing flag in the private ships, as he expressly states that the only difference in the ships of Octavian and Pompey lay in the colours of the towers erected on them. From another passage in Appian[32] it appears that it was the rule for the inferior commander to lower his standard on approaching a superior. It is evident that these standards were not "national" in the sense that our modern flags are national. It is difficult to understand why an invention so apparently simple as the laterally-attached flag should have been so late in making its appearance in Europe (except in the form of small ribbon-like streamers), but the fact remains that it is not until the close of the eighth century A.D. that we meet with evidence of its existence. About the year 800 Pope Leo III caused a mosaic to be placed on the apse of the Triclinium of the Lateran Palace, in which on the right Christ was represented as handing the keys of the Church to Pope Sylvester and a flag to Constantine, while on the left St Peter was handing a pallium to Leo and a similar flag to Charlemagne. Except for some fragments in the Vatican this mosaic has disappeared, but engravings showing it before and after restoration are to be found in a description of the Lateran published at Rome in 1625[33]. In these the flags are depicted as attached by one side to a staff, whilst the fly is cut into three pointed tails. The field in both flags is charged with six roses, but the reproduction made from early drawings by Benedict XIV in 1743, which is still in existence at Rome in the Tribune against the Santa Scala, shows the flag on the right, which is of a green colour, sprinkled with golden stars, not roses. In the year 800 Charlemagne was crowned emperor at Rome, and received from the Patriarch of Jerusalem the keys of that city together with a flag the form of which is not stated. Evidently these flags were symbols of authority, as we have seen the vexillum to have been centuries before.