Recursion with yield return elements order in tree

I have a recursive function that returns all subtree nodes, given the starting root node.

private IEnumerable<Node> getAllNodesRecursively(Node subnode)
{
    foreach (Node node in subnode.Nodes)
        getAllNodesRecursively(node);

    yield return subnode;
}

For the following tree structure:

A
|
+--B
|
+--C
|  |
|  +--D
|
+--E

When I try to iterate as such:

foreach (Node n in getAllNodesRecursively(a))
{
    Console.WriteLine(n);
}

the function returns the only the A value.

I wish to use yield-return with recursion and retrieve elements in the Preorder (A, B, C, D, E in this example).

(If I put the yield return before the foreach, the foreach would never happen).

Is this possible?