Please note that Mommsen uses the AUC chronology (Ab Urbe Condita), i.e. from the founding of the City of Rome. You can use this reference table to have the B.C. dates
From: The History of Rome, by Theodor Mommsen
Translated with the sanction of the author by William Purdie Dickson
No course was left but to despatch in the meantime an embassy to the east for the purpose, first, of obtaining--what was not in the circumstances difficult--the sanction of Egypt to the interference of the Romans in the affairs of Greece; secondly, of pacifying king Antiochus by abandoning Syria to him; and, lastly, of accelerating as much as possible a breach with Philip and promoting a coalition of the minor Graeco-Asiatic states against him (end of 553).
At Alexandria they had no difficulty in accomplishing their object; the court had no choice, and was obliged gratefully to receive Marcus Aemilius Lepidus, whom the senate had despatched as "guardian of the king" to uphold his interests, so far as that could be done without an actual intervention.
Antiochus did not break off his alliance with Philip, nor did he give to the Romans the definite explanations which they desired; in other respects, however--whether from remissness, or influenced by the declarations of the Romans that they did not wish to interfere in Syria--he pursued his schemes in that direction and left things in Greece and Asia Minor to take their course.
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Reference address : https://www.ellopos.net/elpenor/rome/3-08-second-macedonian-war.asp?pg=32