This phrase is used to emphasize what really happened. This could be said in a positive way. Alternate translation: "there was a great disturbance among the soldiers over what had happened to Peter" (See: [[rc://en/ta/man/jit/figs-litotes]])
The abstract noun "disturbance" can be expressed with the words "disturbed" or "upset." Alternate translation: "the soldiers were very disturbed about what had happened to Peter" (See: [[rc://en/ta/man/jit/figs-abstractnouns]])