Yes, but it is poets and song-writers that caused all the problems in the first place! What about “The Death of Nelson” by John Braham, first performed in 1811, causing Emma Hamilton to collapse in hysterics? That has:
'Twas in Trafalgar's bay
We saw the Frenchman lay,
Each heart was bounding then.
We scorned the foreign yoke,
For our Ships were British Oak,
And hearts of oak our men!
Clearly the stress has to be on the second syllable.
But that was very likely the song that changed the word’s previous pronunciation. The Spanish pronunciation stresses the last syllable, and earlier English alternative phonetic spellings were Trafflegar and Traflagar. Clearly the one syllable that was
not stressed was the second syllable!
Maybe that’s what caused the hysterics
Newbolt used the spelling 'Traflagar', and the Monthly Review said that according to Admiral Sir Windham Phipps Hornby, who served under Hardy, the sailors pronounced the word "Traflagar".
There is a footnote in the 1897 NRS publication of Sir George Rooke’s journal as follows:
'Cape Trafflegar – Trafalgar. The spelling shows that the pronunciation in Rooke’s time was Trafălgăr, which is the proper, but not the usual, pronunciation now.' I assume that means the stress was on the first syllable.
I guess that without the BBC, your pronunciation would depend on where you first heard it said, or sung, and if you read it off a chart, you made your own guess!
But Lord Nelson must be a more reliable source than the poets’ efforts to make their verses scan!