Here we have another example in this chapter where the correct phrase “in the defense of X” was changed (although only momentarily) to what is expected in modern English, “in defense of X”. In an earlier instance, discussed under Alma 62:5, the 1874 RLDS omitted the definite article. Here in verse 9, Oliver Cowdery, the scribe in 𝓟, initially omitted the the, then virtually immediately inserted it supralinearly (there is no change in the level of ink flow for the correction). For further discussion of the phrase “in the defense of X” and the tendency to omit the the from this phrase, see under Alma 53:13.
Summary: Maintain the original the in the phrase “in the defense of their country” in Alma 62:9.