purpose: Latin ut + subjunctive ∥ Greek ἵνα + subjunctive after a primary tense
Idiom watch: English 'in order TO + infinitive' must NOT become an infinitive: Latin needs ut + pres. subj. (dēfendant), Greek ἵνα + pres. subj. (φυλάττωσιν). The infinitive of purpose is wrong in both here.
Real instances of this construction, mined from the PROIEL dependency treebanks (Herodotus · Augustus, Res Gestae) — the model you are imitating, attested in the wild. Square brackets [ ] mark letters restored by editors: the Res Gestae survives only in damaged inscriptional copies.
Authored pedagogical model answers, proofread for grammatical correctness in both languages. Not from a single source edition.