Kipling wrote it in response to the German escalation at the beginning of WWI, and probably in direct response to “Haßgesang gegen England” - "Song of Hate Against England" by Ernst Lissauer:
Wir wollen nicht lassen von unserm Haß
Wir haben alle nur einen Haß
Wir lieben vereint, wir hassen vereint
Wir haben alle nur einen Feind:
England
We will never let go of our hate,
All of us have only one hate,
We love united, we hate united,
We all have only one enemy -
England
Lissauer also coined the phrase "Gott strafe England" (God punish England). Oddly enough, he was Jewish (but a dedicated Prussian). He wound up hated by everyone . . . and fortunately for him died in Vienna before Hitler annexed Austria.
Thank you. I was not aware of “Song of Hate Against England” by Ernst Lissauer.