From Halopedia, the Halo wiki
Voidpiercers were developed during the early years of the fledgling Covenant empire, created as a joint design of both Sangheili and San'Shyuum origin as one of the first truly collaborative engineering efforts between the newly-united species. The voidpiercer was developed during an era in which the Covenant's civil and military infrastructure was not yet formalised - as such it was designed with a broad multi-role scope in mind, as opposed to the extreme specialisation of later ships the empire would develop.
Ultimately, the Useumru-pattern's design process was a key factor in testing the ability of the San'Shyuum and Sangheili to cooperate on large-scale engineering efforts - something which would prove vital almost immediately during the construction of the empire's future capital city-station, High Charity.
At least three voidpiercers were present as part of the Prophet of Inner Conviction's fleet at The Refuge in 850 BCE only two years after the signing of the Writ of Union in 852 BCE, in which they took part in the Rending. They would continue to be present around High Charity as the city-station was under construction between 791 BCE and 648 BCE.
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