An Elephant In the Garden by Michael Morpurgo

Lizzie and Karl live with their mother in Dresden, Germany, during WWII.  Dresden hasn't been bombed by the Russians or the Allies yet, but everyone knows it won't be long.  Lizzie's mother is a zookeeper who has taken a special interest in Marlene, a young elephant whose mother recently died.

When the zoo director informs his staff that if Dresden is bombed that the animals will have to be killed to avoid the danger of wild animals running through the city, the family finds new sleeping arrangements for Marlene in their back garden.  The city is bombed while they are taking Marlene for a walk, and they begin a journey across the country to safety.

This is a story about family, friendship, and love inspired by real events in Belfast, Ireland, during the war.