The document presented and discussed in this paper is one of the most important early Latter-day Saint manuscripts associated with both the final months of Joseph Smith's life and the postmartyrdom (or apostolic) interregnum period. Written in late 1844 or early 1845, the document appears to have been drafted for possible use as an official statement by the Twelve concerning Joseph Smith's "last charge" to them, given at a special meeting held in late March 1844, three months before his death. On this occasion, the Prophet conferred upon the Twelve the priesthood keys and authority necessary to lead the Church following his death. The document is a powerful, declarative, united testimony that the Twelve were the authorized legal successors to Joseph Smith. Furthermore, the declaration provides valuable historical information concerning the March meeting—including where the meeting was held, which members of the Twelve were present, and the core of what Joseph Smith said on that occasion.