North & Hillard Ex. 211: a general addresses his soldiers as an approaching enemy is about to encircle them.
The following is to be translated into Latin:
"But since the enemy are already upon us, and we have not collected sufficient provisions, if there should be any here faint-hearted, or any that careth not to fight to the death in his Majesty's cause, let him depart, and not be burdensome to us in the siege."
The Answer Book gives:
"cum vero hostes iam adsint neque nos satis frumenti comparaverimus, si quis timidus adest (aut) si quis non animo paratus est usque ad mortem pro rege nostro pugnare, abeat neve nobis hic obsessis oneri sit."
In "...abeat neve nobis hic obseesis oneri sit.", the siege is about to begin therefore a future tense is required. There is a supine, "obsessum", from verb "obsideo" (= to besiege), in the dative plural, "obsessis" = "to the besieged ones". A verb of motion with a supine gives "in order to" creating a future tense.
LITERAL TRANSLATION (from "abeat"):
"...let him depart (abeat) in order that he (hic) may (sit) not (neve) 'be burdensome' to us the-besieged-ones (nobis obsessis).
The English version asked for adjective, "burdensome" (= "onerosus"); (N & H), in the Latin, gave the noun, "onus", in the dative case, "oneri" (= "to/ for the burden").
Why? How does "oneri" fit in?