Sub T_DATE()
Dim PlgDon As Range, T(), L As Long
Set PlgDon = Sheets("Synthèse").UsedRange
T = PlgDon.Columns("H").Value
For L = 2 To UBound(T, 1)
If VarType(T(L, 1)) = vbString Then T(L, 1) = CDate(T(L, 1))
Next L
PlgDon.Columns("H").Value = T
PlgDon.Sort key1:=PlgDon.Columns("A"), Order1:=xlAscending, _
key2:=PlgDon.Columns("H"), Order2:=xlDescending, _
key3:=PlgDon.Columns("C"), Order3:=xlDescending, _
Header:=xlYes, MatchCase:=False, Orientation:=xlTopToBottom
End Sub