Civil War on Sunday (Magic Tree House Book 21) by Mary Pope Osborne (Paperback, 2000)

Cannon fire! That's what Jack and Annie hear when the Magic Tree House whisks them back to the time of the American Civil War. There they meet a famous nurse named Clara Barton and do their best to help wounded soldiers. It is their hardest journey in time yet--and the one that will make the most difference to their own lives!
Did you know that there's a Magic Tree House book for every kid?

Publisher ‏ : ‎ Random House Children's Books
Publication date ‏ : ‎ 23 May 2000
Language ‏ : ‎ English
Paperback ‏ : ‎ 96 pages
ISBN ‏ : ‎ 9780679890676
Reading age ‏ : ‎ 6 - 9 years
Dimensions ‏ : ‎ 13.2 x 0.5 x 19.4 cm
Book 21 of 40 ‏ : ‎ Magic Tree House