The Summer of the Rosebay Willowherb was the second season in which Tim Churchmouse worked as the Abbey Recorder. The Summer of the Rosebay Willowherb occurred seven seasons after Autumn of the Warriors' Return. This season received its name from the abundance of the pink mauve Rosebay Willowherbs flourishing along the Abbey paths.
This season was marked by the naming of Mattimeo as the new Redwall Champion, succeeding his father in the title. During the ceremony, Mattimeo received The Sword of Martin. Also, Tess Churchmouse gave birth to Mattimeo's son and they named him Martin II after Martin the Warrior.
Stryk Redkite and her new family visited the Abbey once more during that season.
The Summer of the Rosebay Willowherb occurred in the epilogue of Mattimeo.