It imposed on him, as his chief subject, a Celtic tale and a Celtic hero; and though he did his best to de-celticise the story, the vengeance lasts, for the more he did this the more he injured his work.
However, being always a noble artist, he made a good fight for his insularity, and the expression of it harmonised with the pride of England in herself, alike with that which is just and noble in it, and with that which is neither the one nor the other.
Then, too, his scenery (with some exceptions, and those invented) was of his own land, and chiefly of the places where he lived.

It was quite excellent, but it was limited.

But, within the limit of England, it was steeped in the love of England; and so sweet and full is this love, and so lovely are its results in song, that every Englishman has, for this reason if for no other, a deep and just affection for Tennyson.
Nevertheless, in that point also his poetry was insular.

A fault in the poet, not in the poetry.

Perhaps, from this passionate concentration, the poetry was all the lovelier.
Again, when Tennyson took a great gest of war as his subject, he took it exclusively from the history of his own land.