courtship

[KLPNO]

Hi, everybody.
Sometimes I find it difficult to understand the meaning of a some prepositions.
For example what does the preposition 'by' in the following passage.

The early industrialization of Japan, its emergence as a regional power capable of defeating not only China but also Russia, and its courtship by Britain as an ally, were the first illustrations of this trend.

What does the phrase 'its courtship by Britain as an ally' mean - Britain wanted Japan to be its ally or Japan wanted Britain to be its ally?

[diverhank]

I'd say Britain was courting Japan to be its ally, based on "by".

[KLPNO]

Thank you very much, diverhank.