LDS History, 1840 April 15

-- 1840 April 15
Elder O. Hyde left Commerce, on his mission to Jerusalem. (1)

-- 15-16 Apr. 1840
[Lucy Mack Smith] A general conference at Preston, England, for 1,686 members authorizes the publication of a hymnbook and the Latter-day Saints Millennial Star edited by Parley P. Pratt. (2)

-- April 21, 1840
[Joseph Smith] Nauvoo, Illinois. Pursuant to Joseph Smiths direction, the postmaster general officially changed the name of Commerce to Nauvoo. (3)

-- During Apr. 1840
[Lucy Mack Smith] Howard Coray begins clerking for Joseph Smith Jr. (2)

-- 1840 27 May
Millennial Star, first LDS periodical produced outside North America began publication in Manchester, England, with Parley P. Pratt as editor. (4)

-- 1840 May 27
The first number of "The Latter-day Saints' Millennial Star was published at Manchester, England. (1)

-- During 1840, May
First number of Millennial Star published, Manchester, England. (5)

-- During May 1840
[Lucy Mack Smith] Don Carlos Smith and Robert Thompson serve a mission to Philadelphia. (2)

-- 4 June 1840
[Lucy Mack Smith] Lucy Smith (daughter) marries Arthur Millikin. (2)

-- 1840 June 6
The first company of emigrating Saints, from Europe, sailed from Liverpool for New York. (1)

-- June 13, 1840
[Joseph Smith] Emma gives birth to Don Carlos Smith. (6)

-- 13 June 1840
[Lucy Mack Smith] Emma gives birth to Don Carlos Smith at Nauvoo. He is her seventh biological child and sixth son. (2)

-- 1840 June 13
[Lucy Mack Smith] Joseph and Emmas Don Carlos born at Nauvoo. (7)


Footnotes:
1 - Richards - Little, Compendium of the Doctrines of the Gospel, Church Chronology, Ch.66, p.306
2 - Lucy's Book: A Critical Edition of Lucy Mack Smith's Family Memoir, Edited by Lavina Fielding Anderson, 2001, Signature Books
3 - BYU Studies Journal, volume 46, no. 4: A Chronology of the Life of Joseph Smith
4 - http://www.lds.net/forums/scripture-study-forum/12108-church-chronology-1800-2000-part-1-a.html#post214550
5 - Encyclopedia of Mormonism, Vol. 4, Appendix 2: A Chronology of Church History
6 - http://www.prophetjosephsmith.org/joseph_smith_timeline
7 - History of Joseph Smith by His Mother: Revised and Enhanced by Scot Facer Proctor Maurine Jensen Proctor
Mormon History Timeline /Chronology
http://lds-church-history.blogspot.com/