Rubuta ci gaba ga wannan sakin layi - Ya yi aiki a matsayin kyaftin din'yan bindiga a faduwar Antwerp
, inda garin ya mika wuya ga Duke na Parma. Bayan wannan lokacin ya koma Middelburg. A cikin Janairu 1588, Van Os ya auri Margretha van de Piet. Shi da ɗan'uwansa Hendrick sun yi tafiya don samun fata, hatsi da duwatsu masu daraja, galibi a cikin Levant da biranen da ke Tekun Baltic. A shekara ta 1595, ya tafi ya nemi gishiri tare da Isaac le Maire a Setúbal. Van Os ya mallaki fiye da kashi ɗaya cikin bakwai na ƙasar a Beemster.