Cannon
late Middle English: from French canon, from Italian cannone ‘large tube’, from canna ‘cane, reed’ (see cane).
wiktionary
Attested from around 1400 as Middle English canon, from Middle French canon, from Italian cannone, from Latin canna, from Ancient Greek κάννα(kánna, “reed”), from Akkadian 𒄀(qanû, “reed”), from Sumerian 𒄀𒈾(gi.na). Doublet of canyon.
This spelling was not fixed until about 1800. [1] [2]
etymonline
cannon (n.)
c. 1400, "artillery piece, mounted gun for throwing projectiles by force of gunpowder," from Anglo-French canon (mid-14c.), Old French canon (14c.), from Italian cannone "large tube, barrel," augmentative of Latin canna "reed, tube" (see cane (n.)). The double -n- spelling to differentiate it from canon is from c. 1800. Cannon fodder (1847) translates German kanonenfutter (compare Shakespeare's food for powder in "I Hen. IV").