Marie,
I think I misread your question initially, but hopefully I am answering the question you are posing now !
However this is not the partitive des, which would become de before a plural adjective.
Des here is the contraction of the preposition de and the following definite article les
‘ … le sacrifice de ( preposition) les ( definite article ) jeunes soldats… ‘
giving
‘.. le sacrifice des jeunes soldats… ‘
In English, ‘ … the sacrifice of the young soldiers… ‘, not ‘ … the sacrifice some young soldiers…. ‘.
Have a look at section marked attention in the attached lesson
"Des" becomes " de/d' " in front of adjectives preceding nouns (French Partitive Articles)
