I am confused about the usage of "the" before European, British. I am able to find situations where "the" before European, to denote the people of Europe, and the European army to denote the army of Europe. However, I was equally able to find "the" not being used before European when they are denote non-living or emotional things. Like "European raw materials". Please advise me on this!
Perhaps this pair of examples shows the particularisation that the definite article confers on a noun group (and focusing attention solely on the the, if present, before British):
Without the the, we're making a general statement about those species of trees native to Britain.
When the the is included, it indicates that we have some particular subset of some larger set - a collection in a garden centre, or a planting in a large arboretum containing trees from many countries - in mind, and we are conveying that sense.
The British Army is a particular (though not constant) body / organisation, and so takes the.
'Raw materials' would usually be used in a general sense, thus without the the. Unless there is particularisation - pre-reference (again, focusing attention solely on the the before raw materials):
With Europeans, unless a particular subset is being referenced, the the is largely optional:
There is a complicating factor with British. It is not a noun (European is both adjective and noun). But it may be used as a noun (though it retains its classification as an adjective). When those adjectives that may be used this way are used this way, the the is usually mandatory: The rich; the poor; the lame; the British.