Starting from the 1920s due to increasing tension across Asia and Europe in anticipation for war, the British starting building up its military presence at the area and this included the construction of military barracks and the infamous Changi Hospital, with Chinese and Indian labourers brought in from the city. Defences along Changi's southern coast were also beefed up with the construction of machine-gun pillboxes in anticipation of the Imperial Japanese Army arrival by sea. Construction was briefly halted during the Great Depression but was subsequently resumed as these structures were considered vital for the defence of Singapore.