Short idiomatic Dutch translation question

Hi there. I’m reading something old (15th c) and I’ve run into a short phrase I can’t work out:
“. . . zo ghijngen wij jnde zelve kerke alleene met iii of met iiij broeders, ende was up ons vertrecken.”

“Op ons vertrekken?” What does/ did this mean? I’m not finding it in my crappy dictionary and I don’t have a middle-Dutch dictionary and I’m not getting it from web page contexts. Any ideas, cloggies and phlegmmies?

Boy, this plummeted. Just one bump to see if any Dutch or Belgians dopers show up today. . .

Op ons vertrekken? Thus our start? Thus our sailing? Thus our setting out? My purty gud Nederlands-Engels dictionary gives those as translations.

Qad-- did your dictionary list “vertrekken op” as a set phrase, or did you get that via individual words?
‘Thus?’ This isn’t sounding right. . .
Thanks for making my thread less lonely. . . I tend to start sinkers, somehow.

Word for word. But it has optrekken as “start up” and “pull up” and optrekje as “cottage”.

Go figure.