Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
Military is regular. It follows the -ies Conversion rule.
Use plural verbs: "The militaries are ready" (not "is ready").
Yes. The plural militaries is standard across all English variants.
The word military follows the standard English pluralization rule. When forming the plural, military becomes militaries. This follows the -ies Conversion pattern, which is one of the most common plural rules in English.
Understanding why military becomes militaries helps with spelling and pronunciation. Nouns ending in a consonant followed by -y change the -y to -ies in the plural form.
When using militaries in writing, remember that it functions as a plural noun in sentences. It pairs with plural verbs and pronouns. For example: "The militaries are ready" (not "is ready"). This subject-verb agreement is essential for grammatical correctness.