"Forests slow down army movement" translation to Latin

Question

Forests slow down army movement

Silve motum exercitus retardant.

Silva - 1st declension, plural nominative is Silve

motus - 4th declension, in accusative motum

exercitus - 4th declension, in genitive exercitus - movement of an army

retardo, retardare - 1st conjugation, indicative, plural, 3rd person - retardant

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Army movement is slowed down by forests

Motus exerciti a silvis retardatur.

silvis - plural ablative of silva

retardatur - passive indicative, 1st conjugation, 3rd person singular

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Are these translations correct?

In the second one is a the correct word to say by what the movement is slowed?

Am I correct in using ablative of silva here, or should it be stated differently?

I know word order is not the most fixed thing here but probably some kind of order is preferred for this two sentences? Is my word order okay, then?

Answer 1

Forests slow down army movement.
Silve Silvae motum exercitus retardant.

The only error here is misspelling the first word. The plural nominative (and singular genitive and dative) of silva is silvae.

Another question is whether exercitus should be singular or plural. If forests slow down the movement of an army or the army (one at a time), I would go with singular. However, if it refers to movement of armies in general, then I would use plural.

However, the English original is not "the movement of an army", "the movement of the army", or "the movement of armies", but "army movement". In this context "army" behaves much like an adjective, and it might be a good idea to translate it as one. You could use motus militaris (accusative as needed here: motum militarem) for "army movement". It all depends on how you exactly read the English expression "army movement".

Army movement is slowed down by forests.
Motus exerciti exercitus  a  silvis retardatur.

This is a passive version of the first sentence. The subject becomes an agent and the object becomes a subject. This is mostly executed correctly, but there are minor problems.

First, exercitus is fourth declension so the genitive is exercitus. In fact, the genitive stays the same in your two sentences, whether you choose singular or plural. If you choose an adjective instead, it has to be in the same form as motus (masculine singular nominative).

Second, the agent does not always take the preposition a(b). The rule of thumb is that a human agent (some say "animate" instead of "human") takes the preposition, but others don't. For more details, I refer you to this question about deciding which agents are human or animate.

The word order is perfectly fine in both translations.