The Battle of Grand Gulf was fought on April 29, 1863, during th: The verb do can be used as an auxiliary even in simple declarative sentences, where it usually serves to add emphasis, as in "I did shut the fridge." However, in the negated and inverted clauses referred to above, it is used because the rules of English syntax permit these constructions only when an auxiliary is present. Modern English does not allow the addition of the negating adverb not to an ordinary finite lexical verb, as in *I know not—it can only be added to an auxiliary (or copular) verb, hence if there is no other auxiliary present when negation is required, the auxiliary do is used, to produce a form like I do not (don't) know. The same applies in clauses requiring inversion, including most questions—inversion must involve the subject and an auxiliary verb, so it is not possible to say *Know you him?; grammatical rules require Do you know him?[215]