 The cruiser then returned to the Rufiji River so work could begin on overhauling her engines ; the parts would need to be transported overland to the shipyard in Dar es Salaam where they could be rebuilt . While moored in the town of Salale , the ship was heavily camouflaged and defensive arrangements were erected . These included positioning soldiers and field guns to defend the approaches to the cruiser and establishing a network of coast watchers and telegraph lines to watch for hostile ships . An improvised minefield was also laid in the delta to keep the British ships from entering the river . 
