he could remain in namibia for the larger part of the initial stages of his expedition , taking advantage of the geographical anomaly of the caprivi strip* to avoid any necessity for having to cross into angola , and the potential minefield - ho , hum - of border immigration , before linking up with the zambezi river and following that mighty waterway due north , straight through zambia , until it emerged in the democratic republic of congo* from where it looked a relatively easy proposition to pick up the course of the zaire river .