A Continually Developing Series

For a decade and a half, Poul Anderson's Time Patrol series existed as only four stories with no Exaltationists and no Wanda Tamberly. "Delenda Est" was the culmination.

Then:

"Gibraltar Falls" continued the series;

Time Patrolman introduced the Exaltationists;

The Year Of The Ransom introduced Wanda Tamberly and reintroduced Exaltationists;

The Shield Of Time reintroduced both, developed them both further and also developed the basic concept of the series further;

"Star of the Sea" introduced a new concept of variable reality.

"Delenda Est," The Shield Of Time, PART SIX, "Amazement of the World," and "Star of the Sea" are arguably three culminating points of a series that never ceased to develop.