Check the beginning of the book ---- before chapter one. It is a poem that has been around for some time.
Ten little Indian boys went out to dine:
One choked his little self, and then there were Nine.
Nine little Indian boys sat up very late;
One overslept himself, and then there were Eight.
Eight little Indian boys traveling in Devon;
One said he stay there and then there were Seven.
Seven little Indian boys chopping up sticks;
One chopped himself in halves and then there were Six.
Six little Indian boys playing in a hive;
A bumble bee stung one and then there were Five.
Five little Indian boys going in for law;
One got into Chancery and then there were Four.
Four little Indian boys going out to sea;
A red herring swallowed one and then there were Three.
Three little Indian boys walking inthe Zoo;
A big bear hugged one and then there were Two.
Two little Indian boys sitting in the sun;
One got frizzled up and then there was One.
One little Indian boy left all alone;
He went and hanged himself
And then there were None.
Because the word Indian became politically sensitive, some versions, such as the one in your book, use the word Soldier
In the book it says Ten Little Soldier Boys
Same exact poem but with soldier boys instead on little indians