Also seen translated as Yoshitoshi's Warriors Trembling with Courage, this series consisting of thirty-three prints was another extremely popular series designed by Yoshitoshi, as at least five versions of each print in the series were issued.  The series was originally published by Kobayashi Tetsujirō 小林銕次郎 (Maruya Tetsujirō 丸屋銕次郎) from December 1883 through October 1886, and was also republished by Tsunajima Kamekichi 綱島亀吉(Tsujiokaya Kamekichi 辻岡屋亀吉) in 1886.  The Tsunajima series can generally, but not always, be distinguished by the shape of the signature cartouche, a rectangular cartouche with square corners rather than a rectangular cartouche with rounded corners.  Some sources note that the prints issued by Kobayashi Tetsujirō always have a multi-color title cartouche but, in at least one case, the earlier published print has a simple white title cartouche.  As the publisher's name appears in the left margin of all prints that I've encountered from this series, assuming the left margin is intact, then a simple examination of the publisher's name will tell the tale.

When Yoshitoshi designed this series it was towards the end of his career when he was about forty-four, just before his most famous series One Hundred Aspects of the Moon was issued. "The [Courageous Warriors] compositions depict famous warriors from Japan’s past with an intensity and detailed care that demonstrate Yoshitoshi’s reverence for the role long played by warriors in the formation of Japan."¹  "The subject matter of Yoshitoshi’s courageous warriors is drawn mostly from the history of the late Heian period, in particular, the Genpei wars (1180-85) between the Taira (Heike) and Minamoto (Genji) clans and the Warring States period of the mid-15th to late 16th century."²

¹ website of the Brooklyn Museum https://www.brooklynmuseum.org/opencollection/objects/173661
² Yoshitoshi, Masterpieces from the Ed Freis Collection, Chris Uhlenbeck and Amy Reigle Newland, Hotei Publishing, 2011 p. 116.