The Singapore Army is the land service branch of the Singapore Armed Forces (SAF). The largest of the four branches of the SAF, the Singapore Army traces its origins to the 1st Battalion, Singapore Infantry Regiment (1 SIR), which was formed in 1957, when Singapore was still under British colonial rule. After Singapore had gained independence, the Singapore Army Bill was passed in Parliament on 23 December 1965, and National Service (NS) was subsequently introduced in 1967. Mostly made up of conscripts, the Singapore Army can mobilise all operationally-ready military reservists in the event of war or national exigencies.