Sentence:  Major Lawrence returned answer, 'that the English colours were carried on the <WSD>flag gun</WSD> of their artillery, which if Mons. D'Aotenil would look out for, he might thence discover where the English were posted ; and that, although he was as unwilling as himself to spill European blood, yet if any shots came that way he should certainly return them.' 
Meaning of the word marked with <WSD> tags:  A gun in an artillery train bearing a flag.