Première Macro

Sub DateFrancaise()
Dim tablo1(), tablo2(), lig As Long, txt As String, m As Variant
tablo1 = Array("JAN", "FEB", "MAR", "APR", "MAY", "JUN", "JUL", "AUG", "SEP", "OCT", "NOV", "DEC")
tablo2 = Array("janv", "févr", "mars", "avr", "mai", "juin", "juil", "août", "sept", "oct", "nov", "déc")
Application.ScreenUpdating = False
On Error Resume Next
For lig = 1 To Range("A65536").End(xlUp).Row
  txt = Cells(lig, 1)
  txt = Application.Trim(txt) 'supprime les espaces superflus (sécurité)
  txt = Replace(txt, "2 DATE ", "")
  m = Application.Match(Split(txt, " ")(1), tablo1, 0)
  Cells(lig, 1) = Replace(txt, tablo1(m - 1), tablo2(m - 1))
  Cells(lig, 1) = CDate(Cells(lig, 1)) 'pour les années >= 1900
Next
Columns(1).NumberFormat = "d mmm yyyy"
End Sub