[words_and_signs]

This is wrong. It's a good rule of thumb because passive voice can be a common indicator of weak writing, but it has plenty of good uses in strong writing. The best case to apply it is when the object of a sentence was previously a subject or other focus of prior sentences, and so is more familiar to the reader than the subject of the new sentence. For example:

"The United States had maintained neutrality until 1941. However, it was attacked at Pearl Harbor, and then chose to enter the war."

[SamPatt]

"The United States was neutral until the Japanese attacked Pearl Harbor in 1941, leading them to enter the war."

I'd say active is still better here.

[suyjuris]

I would disagree. This sentence is about the Unites States, not Japan, and the use of passive voice reflects that.

[selfmodruntime]

This is disingenuous. Removing the bad actor in this sentence removed part of the cause for the effect. Not an attack happened, a japanese attack happened.

[suyjuris]

I you feel that the actor is an important part of the sentence, you can include it in passive voice as well: “However, it was attacked at Pearl Harbor by Japan, and then chose to enter the war.”

[alanh]

How and why is that possibly better than saying "the Japanese attacked them at Pearl Harbor"? The passive voice is what enables the omission of the actor.

[CameronNemo]

Could also just say "the attack on". Then you don't shift focus or use the passive voice.