The first modern genocide (if you don't count the Congolese, which most don't but should) was a death march. The Turks didn't try to eliminate the Armenians by shooting or poisoning or slashing them; they simply made them walk, en masse and in horrible conditions, until they died.

If you've supplanted an ethnic group's government and redirected resources such that people start dying in horrifically large numbers, that is also a case in which you're committing genocide. Even if you're the Brits.