Complex sentence: The proof advanced in this paper was confirmed during the 1999 renovation, during which evidence was uncovered pointing to the construction of an entirely new sloop-of-war of the 1850s era.
Split into simpler sentences: The proof advanced in this report was confirmed during the 1999 renovation. At that time evidence was uncovered pointing to the construction of an entirely new sloop-of-war of the 1850s era.