为国捐躯 gave one life for one's country/ died for one's country/ died in the service of one's country
They died for their country.
他们为国捐躯.
He died fighting for his country.
他为国捐躯了.
He died in the service of his country.
他为国捐躯.
Many a man has lived and died for his country.
好多人为国尽忠,为国捐躯.