Complex sentence: The resulting steady stream of disgruntled, Dutch speaking, trained marksmen leaving the Cape not only hobbled the Dutch capability to crew their commandos, but also created very belligerent, skilled groups of opportunists that harassed the indigenous populations the length of the Orange River.
Split into simpler sentences: The resulting steady stream of disgruntled, Dutch-speaking, trained marksmen leaving the Cape hobbled the Dutch capability to crew their commandos. It also created very belligerent, skilled groups of opportunists who harassed the indigenous populations the length of the Orange River.