Shìbīng yòng pēnhuǒqì shāohuǐ le dífāng de gōngshì.
The soldiers used flamethrowers to burn down the enemy fortifications.
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Pure compositional name: 喷 ('to spray/spurt') + 火 ('fire') + 器 ('device/instrument'). Same 器 suffix as in 武器 'weapon,' 仪器 'instrument,' and 灭火器 'fire extinguisher' (literally 'extinguish-fire-device,' the opposite operation).