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
Meanwhile, however, the occasion for declaring war, which Rome desired, had been furnished from another quarter. The Athenians in their silly and cruel vanity had put to death two unfortunate Acarnanians, because these had accidentally strayed into their mysteries.
When the Acarnanians, who were naturally indignant, asked Philip to procure them satisfaction, he could not refuse the just request of his most faithful allies, and he allowed them to levy men in Macedonia and, with these and their own troops, to invade Attica without a formal declaration of war. This, it is true, was no war in the proper sense of the term; and, besides, the leader of the Macedonian band, Nicanor, immediately gave orders to his troops to retreat, when the Roman envoys, who were at Athens at the time, used threatening language (in the end of 553). But it was too late.
An Athenian embassy was sent to Rome to report the attack made by Philip on an ancient ally of the Romans; and, from the way in which the senate received it, Philip saw clearly what awaited him; so that he at once, in the very spring of 554, directed Philocles, his general in Greece, to lay waste the Attic territory and to reduce the city to extremities.
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Reference address : https://www.ellopos.net/elpenor/rome/3-08-second-macedonian-war.asp?pg=35