Learn Italian: L'esercito ha salvato l'equipaggio.

In Italian, collective nouns like l'esercito (the army) and l'equipaggio (the crew) are strictly singular because they refer to a single group. Even though an army consists of many soldiers, you must always use the singular form of the verb. That is why we use ha salvato (it rescued) instead of the plural hanno salvato.

Is l'equipaggio related to the English word equipment?

They share a historical root, but l'equipaggio specifically means the crew of a ship, plane, or other vehicle. If you want to talk about physical equipment or gear in Italian, you would use words like l'attrezzatura or l'equipaggiamento.

Could I use the imperfect tense here and say L'esercito salvava l'equipaggio?

You could, but it changes the meaning. The passato prossimo (ha salvato) shows that the rescue was a single, successfully completed event. Using the imperfect (salvava) would mean the army was in the process of rescuing the crew, describing an ongoing action in the past without telling us if they actually succeeded.

Why do both esercito and equipaggio take the article l'?