The word aller has called forth a great variety of etymological explanations, none of which is completely satisfactory to the linguistic scholar. However, I make bold to offer a fresh contribution to the problem, in the hope that it will fulfill all three requirements of a good etymon, phonological, historical, and semantic. The well-known hypothesis, that aller comes from the rapid giving of military commands, ambulemus, *amlemus, *allemus , offers serious phonological difficulties. Not only does ambulare give embler regularly in Old French, but, in addition, both ambulare and alare appear in the Reichenau Glosses. Furthermore, it is not necessary to seek a common etymon for the verb 'to go' in Romance, since the very confusion of forms existing in the conjugation of this verb in all the Romance tongues is enough warrant for positing a separate origin for the Northern French aller.
Warren F. Manning (Wed,) studied this question.