Windows NT *at least* since Vista, but probably XP already, and maybe
even the original NT 3.51, support the forward slash in the command
line.
ForwardSlash works since MSDOS !
From wikipedia "Backslash" :
"The Windows API can accept either the backslash or slash to separate
directory and file components of a path, but the Microsoft convention is
to use a backslash, and APIs that return paths put backslash in.[7]
MS-DOS 2.0 copied the hierarchical file system from Unix and thus used
the forward slash, but (possibly on the insistence of IBM) added the
backslash to allow paths to be typed into the command shell while
retaining compatibility with MS-DOS 1.0 and CP/M where the slash was the
command-line option indicator (i.e. as in typing "dir/w" to give the
"wide" option to the "dir" command).[8] Although the command shell was
the only part of MS-DOS that required this, the use of backslash in
filenames was propagated to most other parts of the user interface"