When attack is a noun, the preposition on is preferred with locations, e.g.;
- attack on Pearl Harbour
- attack on Fort Sumter
- attack on (a) French church
- South Korea, US to simulate attack on nuclear facility (CNN)
If attack is used as verb, no preposition is necessary. All the examples below are taken from Google news
- ... attacked a homeless man
- ... attacked people at a shopping mall.
- seagull attacked customers
- ... attacked a humanitarian aid convoy
Compare the results for attack on Israel (blue), attacked Israel (red), attack Israel (green), and attack against Israel (yellow). All four are grammatical, but the first suggests that attacks on Israel are seen as acts of aggression aimed at a specific location rather than a nation. But it is a subjective point of view, so it would be interesting to hear from other native speakers.
In the example cited by the OP, the acid was thrown (at) or poured on the woman. The woman's body is considered a surface. The preposition on is used to express physical contact with a surface.
a horrific acid attack on a pregnant woman
The main meaning of against is in "opposition to", in the following examples, against could be substituted with on.
- UN officials condemn attacks against (an) aid convoy
- his attacks against a Hispanic federal judge
- more attacks against Israeli soldiers and civilians
- Pakistan has initiated a string of attacks against India including major ...
However, between attack somebody and attack against somebody, the first preposition is usually preferred. Ngram illustrates that attacked him (blue line) is far more common than attack against him (green line)
What is it called when the preposition is omitted? It's called an indirect object.
That's what an indirect object is. An indirect object is licensed and governed by a verb. When a preposition is involved, the object is a prepositional object or an oblique object.
Oddly enough, the cited dictionary page doesn't manage to offer a clear example of this verb's ditransitive use. The example "he was awarded the Military Cross" is cast in the passive voice. The ditransitive construction is more obvious in the active voice: "They awarded him the Military Cross." The example "a 3.5 per cent pay rise was awarded to staff" is not a ditransitive example, even when cast in the active. "Management awarded a 3.5% raise to the staff" includes a direct object and a prepositional object, but there is no indirect object in sight.
You don't seem to be confused by the ditransitive use of this verb in the active voice. However, passive-voice participles do seem to confuse you.
Such confusion is easy to understand. For most verbs in English, the past-tense forms and the so-called past participle forms are identical. Even the "past participle" label is confusing, given that participles have no tense.
"The Academy awarded the Oscar" looks quite similar to "the actor awarded the Oscar". Without further context, they both can be parsed as clauses in the active voice and past tense. However, "the actor awarded the Oscar has refused to accept it" requires a different parsing. Here, "awarded" is a participle, "awarded the Oscar" is a participial phrase which modifies "actor", and "the actor awarded the Oscar" serves as the complete subject of "has refused to accept it".
You're not the only one experiencing such confusion. It's nearly universal. Sentences like "the actor awarded the Oscar has refused to accept it" are garden-path sentences. It is easy for anyone to assume that "awarded" is a finite verb until the phrase "has refused" is encountered. Since "has refused" is finite and must have a subject, we have no option but to re-parse "awarded" as non-finite and without subject.
The examples that you provided are not garden-path sentences. Each one contains a clue to the participial nature of the verb in question before it is encountered:
The phrase "on the plaque awarded her" has "on", a preposition which licenses an object. The phrase "the plaque" cannot serve as the subject of "awarded" since it serves as (a part of) the object of "on". A similar explanation serves for the prepositional phrases "about the Nobel Prize awarded Ernest Hemingway" and "by the Oscar awarded Michael Radford's Il postino . . .". In "who refused the Oscar awarded him", "the Oscar" is (a part of) the direct object of "refused". In the absence of a subject, there is no clause and there is no reason to assume that the verb's form is finite.
Best Answer
Your brother used to fight with you. To say that he fought against you would imply that you were enemies.