Singapore's reservoir and the besieger's food supply

A counterfactual defence of Singapore turns on holding the reservoir while the Japanese army's food supply deteriorates. In the simulation described here, British troops occupy the prepared defensive positions and retain the reservoir. The advancing Japanese force then suffers catastrophic starvation within roughly a week, although the timing is disputed. This is a conditional scenario rather than the historical outcome of the battle. The outcome depends on the besieger exhausting its supplies while the defenders hold out. An attacking army also needs a sustainable food supply, and can lose a siege when that supply breaks down.