The Singapore Self-Propelled Howitzer 1 (SSPH 1) Primus[1] is a self-propelled howitzer armed with a 155 mm howitzer. Developed jointly by the Singapore Armed Forces (SAF), Defence Science and Technology Agency (DSTA) and Singapore Technologies Kinetics (ST Kinetics), it was officially inducted to the Singapore Artillery in 2004. Primus is derived from the Artillery motto In Oriente Primus (Latin: “First in the East”).

At the time of introduction in 2002, SSPH Primus was recognized as the world’s lightest 155mm, 39 calibre tracked howitzer of its kind.[2]