With his last strength / in his final effort
When he was already very weak or exhausted.
(The New Hebrew)
Translation
Expression (Hebrew)
בְּכוֹחוֹתָיו הָאַחֲרוֹנִים
Definition (Hebrew)
כְּשֶׁהוּא כְּבָר הָיָה מַמָּשׁ חַלָּשׁ אוֹ עָיֵף.
(הָעִבְרִית הַחֲדָשָׁה)