Events that occurred on 4 March.
 On Earth
- 1914 - Tolkien submits an essay on his favourite poet, Francis Thompson, to the Oxford Essay Club.
- 1937 - Tolkien's poem "Iúmonna Gold Galdre Bewunden" is re-published in The Oxford Magazine.
- 1938 - Tolkien writes Letter 26.
- 2010 - The History of Middle-earth is re-released in hardcover.
 In Arda
- T.A. 3019:
- Gandalf and Erkenbrand show up and finish the Battle of the Hornburg.
- Théoden and Gandalf set out for Isengard with a guard of twenty Rohirrim. They pass the tombs of the Fords of Isen.
- The River Isen is restored to its original course.
- Frodo, Sam and Gollum reach the slag-mounds on the edge of the Desolation of the Black Gate.