Firstly - That woman is on steroids and steroids didn't come about until the 1960's.

Secondly - Muscular size doesn't not necessarily equate to strength, or at least optimal strength. Strength is a skill; olympic weightlifters are very good at olympic weight lifting but won't be as good, at the same weight class, as a strongman competitor or a powerlifter at their respective sports, for example. You've shown a picture of a bodybuilder and, generally speaking, they are nowhere near the height of their strength potential because they do not train specifically for it. They want optimal sarcoplasmic hypertrophy and not much of anything else. They're not "weak" in the conventional sense of the word but they're generally not as strong as athletes who weigh similar amounts but train for strength performance.

Are you thinking of a particular country/time period?

Also, I think you might be mistakenly assuming that the reason for the exclusion of women is based on their actual capacity to fight - when (depending on what time period/place we're talking about) there are likely a whole host of cultural reasons why women would be barred from combat roles.