translation of "lors du"

Question

Looking at the sentence: Lors du Congres organisé(...clause), un très large majorité des cent quatre vingt huite members se prononce pour l'etabissement d'une monarchie constitutionnelle. I would translate this as "whilst the congress organised, a very large majority decided on the establishment of... So would have anticipated "Lorsque le Congres..." or "Quand le Congrès..." Where as "Lors du..." seems to have the meaning "While the..." "During the..." ...so the definite article seems not needed... can anyone clarify the use of "Lors du..." here I wonder...?

Best regards,
Michael

Maarten Kamp · Accepted Answer

< Lors de  >  - during, as translated in the exercise. Lors de (le Congrès) - during (the) Congress - (de le) contracts to “du”.
While in English “the” may be dropped in a similar sentence, the definite article is not dropped in French.