Almost nothing is known of Alexander Whitesides. There is not
even an identifiable entry in the Ancestral File. We may guess that
Alexander was born between 1795 and 1812 and probably in the Northeastern
United States. Alexander is mentioned in the History of the Church
only two times.
We do know that in 1834 he participated in Zion's Camp, the expedition to provide relief to the saints in Missouri. Since most
of these were young men, we may guess that Alexander was also. And since
most members of the Church at that early date were from the Northeastern United States, we
might guess that Alexander was also from that locale.
As long as we are speculating, we might guess that he was related to Isaiah Whitesides and Morris Whitesides, both of whom are mentioned in the History of the Church but not in such a way as that positive identification may be made.
We may also infer that he performed in Zion's Camp
with a supportive attitude as he was ordained a Seventy and called into
the First Quorum of Seventy in 1835, thereby entering the ranks of the General Authorities.
Grampa Bill knows absolutely nothing more of Alexander Whitesides... and doesn't even have any more speculation.
Smith, History of the Church, Vol.2, pp.185, 203