Harold Sharfman, in "The First Rabbi" writes:
That year, (1870, HT) there arrived in America, a unique personality, a Jerusalemite, a Judean diplomat without portfolio, who became an American citizen before returning to the Land of Israel. He was Hayyim Zevi Sneersohn, a grand-grandson of Shneor Zalman, Rabbi of Liadi, the founder of Chabad Chasidism.
Reb Chayim Tzvi was, according to Loebtree, the great grandson of The Alter Rebbe, and a grandson of HaRaHa"K Reb Moshe N"E. He had immigrated to then-Palestine with his mother in 1840 (aged 8?) and was recognized as a prodigy. By 1860 he was traveling to the Far East and as far as Australia to raise funds for the poor of Israel.
In May 1870 he traveled to Cincinnati, where he told audiences that he felt he could discern the finger of G-d pointing to a day "not far distant, he hoped, when the great deliverance would take place and the land [of Israel] be restored to the Jewish people."
"He stressed the need to purchase land and erect buildings, because the restoration would not be accomplished just by the word of G-D. He pointed out that Abraham too, bought land, even though it had been divinely promised to him."
He had one son, Moshe, no grandchildren are known. He passed away in South Africa in 1881-1882 as a young man, while raising funds for the Needy of Israel.