Translate the following English sentence to French:
"Through the measures they have taken, the Heads of State and Government of the Fourteen have really burdened themselves with an enormous responsibility in relation both to Austria and to the Union as a whole."
En adoptant leurs mesures, les chefs d'État et de gouvernement des Quatorze se sont à vrai dire chargés d'une lourde responsabilité, tant vis-à-vis de l'Autriche que de l'Union.