Joseph was the first to master his feelings, and, raising Brother Scott's arms from off his neck, he said, in a deep and sorrowful tone: "I fully comprehend it!" He then relaxed into a solemn study, while his brethren anxiously watched the changes of his countenance as if they would read the thoughts and feelings that mere preying upon his heart. The scene was painful and impressive. Each moment they expected to hear him say that his work on earth was done and that he would have to be slain to seal his testimony. After a long silence he finally continued: "Brethren, I am going to leave you. I shall not be with you long; it will not be many months until I shall have to go." This remark still left them in doubt as to his future fate, but had such significance that Brother Scott again anxiously inquired: "Brother Joseph, are you going to be slain?" Joseph, for some reason, evaded a direct reply, but continued in a tone that told too plainly of the sorrow he felt: "I am going away and will not be known among this people for twenty years or more. I shall go to rest for a season." This reply did not clear away their  doubts any more than the former one, but it was evident he intended to leave the people and keep hid more closely than he ever had done, or else, with prophetic vision, he discerned the final outcome of his enemies' efforts, and, through compassion, forebore to crush the spirits of his brethren by telling them plainly the whole truth. Subsequent events leave us still in doubt as to the real purport of his words. The dark clouds of persecution from enemies without, fearfully augmented by traitors from within, grew so threatening toward the close of the Prophet's life, that he saw something must be done for the safety of himself and the people. He therefore conceived the idea of moving the Saints once more, and this time far beyond the cruel blasts of persecution, and seek shelter behind the barriers of the Rocky Mountains. He called for a company of volunteers to explore the great West and find the most suitable place for the Saints to settle. Quite a number volunteered and began to make preparations for the journey. It is a well known fact that just previous to surrendering himself to be taken to Carthage, Joseph got into a boat and started across the river, evidently to evade his enemies. He intended to keep out of their hands until this company had procured a suitable outfit for such an undertaking, when he would have accompanied them. Some of his brethren, however, begged him not to desert the people in such a time of trouble and danger, and at their importunity he returned to Nauvoo, and we all know the result. He was induced to surrender himself to the officers of the law, was cast into prison, and there cruelly murdered by a bloodthirsty mob. Perhaps in reply to Brother Scott's question, Joseph was revolving these plans in his mind and looking forward to the time when he and the Saints would be beyond the reach of persecution; it is now impossible to tell, but the events which followed rather indicate that he foresaw his death. However, he continued in great earnestness: "They accuse me of polygamy, and of being a false Prophet, and many other things which I do not now remember; but I am no false Prophet; I am no impostor; I have had no dark revelations; I have had no revelations from the devil; I made no revelations; I have got nothing up of myself. The same God that has thus far dictated me and directed me and strengthened me in this work, gave me this revelation and commandment on celestial and plural marriage, and the same God commanded me to obey it. He said to me that unless I accepted it and introduced it, and practiced it, I, together with my people, would be damned and cut off from this time henceforth. And they say if I do so, they will kill me! Oh, what shall I do? If I do not practice it, I shall be damned with my people. If I do teach it, and practice it, and urge it, they say they will kill me, and I know they will. But," Said he, "We have got to observe it. It is an eternal principle and was given by way of commandment and not by way of instruction." It will be seen from these outbursts of his soul what a conflict was going on in his mind, and the agony that he endured can only be imagined by those who knew his sensitive and generous spirit. Persecution and imprisonment from the hand of an enemy would be passed by almost unnoticed when compared with these murderous thrusts from the daggers of alienated friends
Death, to a man who was so familiar with the unseen world and the happiness to be enjoyed there, was stripped of its terrors. His fear of simply losing his life caused him little anxiety. But his whole soul was in the work which the Lord had given him to do, and such bloodthirsty opposition to a commandment of God among his brethren caused the greatest anxiety and grief. His greatest trials are no doubt hid deepest from our view. The consultation lasted for a long time before they separated to their homes, and impressions were made on the minds of our two young heroes that will last forever. They got an insight into the life of the Prophet and the na-ture of the work he had to perform, that had never before entered their imaginations. Their love for him and the cause in which he was laboring was increased, and gladly would they have laid down their lives to have saved his. Before separating, however, Joseph placed a seal upon the boys' lips, and made them promise that they would not reveal what had transpired that day to a living soul--not even to their own fathers, for at least twenty years. The object of placing this injection upon them no doubt was for their own safety, as their lives would probably have been taken if any of the conspirators should ever find but that any of their proceedings had been revealed. The boys kept their promise, and now, after a lapse of so many years, these important facts, which throw light upon many of the acts and sayings of Joseph Smith, which his brethren could never before fully understand, are revealed and placed with other important records in the archives of the Church. The muse of history, too often blind to true glory, has handed down to posterity may a warrior, the destroyer of thousands of his fellowmen, and left us ignorant of the valorous deeds of real heroes, whose lot chanced to be more humbly cast; but in that day, when all men's actions will be revealed upon the housetops, we shall no doubt see the names of Denison L. Harris and Robert Scott among the world's heroes as stars of no small magnitude. "Fact is stranger than fiction," And in value they cannot be compared. I respectfully submit the above narrative, which is a true recital of events that actually transpired. The manuscript has been carefully scrutinized by proper authorities who are satisfied of its authenticity and have approved its publication, as an important and accurate item of history connected with the Church. Horace Cummings.
(Taken from The Contributor, Vol. V, pp. 251-260.)
The conspiracy of Nauvoo, was by the Nauvoo members and the Leaders that took over after Joseph Smith death; about all leaders down to today in Salt Lake have been decedents of Nauvoo.
The Lord promised, that if they built the Nauvoo temple, and dedicated it, they, the Saints and the Church would not be moved out of their place, the Lord would protect them. That did not happen, so one is left to conclude that the Church at that point, fell under condemnation; the higher Priesthood and blessings was not passed, they died with Joseph; read D & C 124
The real conspiracy with Nauvoo, was that the Temple was never fully completed and dedicated, and the Lord placed the Church under a curse.
Why was Joseph persecuted in the first place, it was because he tried to keep hidden certain things that he called sacred when others saw it as sacrilegious and downright in opposition to what they knew was taught to them in the Bible. Polygamy was the center stage and main reason for the animosity against Joseph not only from outsiders but from his own ranks. If he left that out things would probably have turned out differently.