Matar, Morir, Mató, Murió etc.
 

Pensé que tenía esto, pero ahora estoy confundido.

Un soldado británico murió mientras retiraba minas.
A British soldier was killed while clearing mines.
died

Un soldado fue matado... was killed....
Un soldado murió... died.....

Se puede usar murió=was killed?

The correct translation of 'murió' is 'died'.
The preterit tense was used in the original statement, which was written using the active voice.
A correct English translation should have also appeared in the active voice:
A British soldier died while clearing mines.

This is an example where you say it one way in Spanish but you can say it various ways in English.

Murió means died which can include being killed (one way of dying) depending on context. In this particular context in English we would use "died" or "was killed" interchangeably because it's understood that the mines were responsible for the death.

In spanish when I hear "fue matado" I think homicide or assassination. So if you say "Un soldado fue matado mientras retiraba minas", I would understand that maybe while he was working, someone else (a guerrilla fighter or an enemy soldier") had killed him. But it wouldn't be clear.

Gracias a todo por la ayuda. Poco a poco aprendo mas.

Let me add a little note: "fue matado" sounds incorrect for many native speakers, and I agree that if used, it would necessarily imply a murder. :thinking:
I think that since "matar" is the worst action, the verb doesn't really match passive voice for some of us.
When the passive voice is used, in the news for example, you may find "fue muerto" instead:
- El ladrón fue muerto a manos del policía.
Yet, I think most of us will still prefer some other solution in active voice: "el policía mató al ladrón", "el ladrón murió por los disparos del policía"... things like that.

In your example I would prefer "un soldado británico murió mientras retiraba minas".
Maybe more formally: "un soldado británico perdió la vida durante el proceso de desminado..."

you'll hear "fue asesinado" and "murió asesinado"

Agreed, but only when they've been murdered.
In the case of the policeman and the thief, the police is not supposed to murder, but to righteously kill, so we can't use "asesinar" there.
By the way, the Diccionario Panhispánico de Dudas says that "fue matado" is normally substituted for "fue muerto" despite the fact that both participles belong to different verbs, because the verb "morir" used to be causative in archaic Spanish. :)