Yes, The Last Oath is definitely a goth band because most of their albums belong to the Gothic Rock and Deathrock genres, which are among the core subgenres of goth music. Albums like Palynsyndrome, Smile Of The Moon, and Pernicious are examples of their goth sound.
The Last Oath is located in France, Pictavia, active in 2013 — present. You can find more information about The Last Oath on their GothDB band page.
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