"(zero article) failure" but "the departure": articles before mass nouns

A quote from The Economist:

In Iraq failure to reach a similar security agreement led to the
sudden and premature departure of all American forces.

Here we have two nouns which may be either mass or count according to Oxford Dictionary. One has a zero article (failure), the other takes THE (departure).

Filling in articles (which were pre-cut in a text editor), I've committed two mismatches with The Economist's version, as follows:

In Iraq *the failure to reach a similar security agreement led to *a
sudden and premature departure of all American forces.

I thought that the noun "failure" here is a mass noun, yet modified enough (which failure? - "to reach a similar..") to merit the definite article.

Concerning the "departure", I'd consulted Oxford Dictionary which states that the word may be used as a count noun: "she made a hasty departure". Besides, the troops' departure may well be unknown to the reader, hence "A".

Assuming both nouns are mass nouns in this sentence, I have two questions:

1. Can we still use "THE" with "failure"? Or does it need to have an "of-phrase" modifying it in order to take THE? ("..the failure of the government to reach..")




2. Can we use zero article with "departure"? (despite the post-modification by an "of-phrase"; It seems to me that "of-phrases" are powerful inducers of THE-ification.)

And still it puzzles me why "departure" here cannot be a count noun, like in "she made a hasty departure".

Answer

Yes on both counts.

When you say you made two mistakes, I disagree. I guess your teacher is a grammar Nazi…