i was using this (latin available here) translation of caesar's commentary on the gallic war, and i noticed that they translated frumenti as corn, which made no sense to me since corn (maize for the rest of this post) as i knew of it wasn't brought over to europe until the late 15th century, but it turns out that the word corn in english has been around longer since before maize was brought to europe. behold the following definition:

1. a. gen. A small hard particle, a grain, as of sand or salt.

as well as a usage (and apparent definition) contemporary to the translation i'm using:

1876 Mid-Yorksh. Gloss., Corn, a grain, or particle, a ‘corn of tobacco’, a ‘corn of powder’, a ‘corn of rice’.

both of which were retrieved from the OED. so, it appears that, no, my translation isn't wrong (as was my first suspicion) but rather that my understanding of the word corn was faulty.