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
Literature Subsidiary to History - Caesar's Report
The minor historical literature of this period displays on the other hand, amidst many insignificant and forgotten productions, one treatise of the first rank--the Memoirs of Caesar, or rather the Military Report of the democratic general to the people from whom he had received his commission. The finished section, and that which alone was published by the author himself, describing the Celtic campaigns down to 702, is evidently designed to justify as well as possible before the public the formally unconstitutional enterprise of Caesar in conquering a great country and constantly increasing his army for that object without instructions from the competent authority; it was written and given forth in 703, when the storm broke out against Caesar in Rome and he was summoned to dismiss his army and answer for his conduct.(32)
32. That the treatise on the Gallic war was published all at once, has been long conjectured; the distinct proof that it was so, is furnished by the mention of the equalization of the Boii and the Haedui already in the first book (c. 28) whereas the Boii still occur in the seventh (c. 10) as tributary subjects of the Haedui, and evidently only obtained equal rights with their former masters on account of their conduct and that of the Haedui in the war against Vercingetorix. On the other hand any one who attentively follows the history of the time will find in the expression as to the Milonian crisis (vii. 6) a proof that the treatise was published before the outbreak of the civil war; not because Pompeius is there praised, but because Caesar there approves the exceptional laws of 702.(p. 146) This he might and could not but do, so long as he sought to bring about a peaceful accommodation with Pompeius,( p. 175) but not after the rupture, when he reversed the condemnations that took place on the basis of those laws injurious for him.(p. 316) Accordingly the publication of this treatise has been quite rightly placed in 703.
The tendency of the work we discern most distinctly in the constant, often--most decidedly, doubtless, in the case of the Aquitanian expedition (Cf. III. XI. The Censorship A Prop of the Nobility)-- not successful, justification of every single act of war as a defensive measure which the state of things had rendered inevitable. That the adversaries of Caesar censured his attacks on the Celts and Germans above all as unprovoked, is well known (Sueton. Caes. 24).
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Reference address : https://www.ellopos.net/elpenor/rome/5-12-religion-culture-literature-art.asp?pg=75