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
It is a significant indication of the relations subsisting among the Spaniards themselves, that the emissaries of the Roman party subsisting among the Arevacae were the chief occasion of the rejection of the proposals of peace at Rome, by representing that, if the Romans were not willing to sacrifice the Spaniards friendly to their interests, they had no alternative save either to send a consul with a corresponding army every year to the peninsula or to make an emphatic example now.
In consequence of this, the ambassadors of the Arevacae were dismissed without a decisive answer, and it was resolved that the war should be prosecuted with vigour. Marcellus accordingly found himself compelled in the following spring (603) to resume the war against the Arevacae. But--either, as was asserted, from his unwillingness to leave to his successor, who was to be expected soon, the glory of terminating the war, or, as is perhaps more probable, from his believing like Gracchus that a humane treatment of the Spaniards was the first thing requisite for a lasting peace--the Roman general after holding a secret conference with the most influential men of the Arevacae concluded a treaty under the walls of Numantia, by which the Arevacae surrendered to the Romans at discretion, but were reinstated in their former rights according to treaty on their undertaking to pay money and furnish hostages.
Do you see any typos or other mistakes? Please let us know and correct them
Reference address : https://www.ellopos.net/elpenor/rome/4-01-gracchi.asp?pg=9