  We revisit the well-studied D0-D4 system of D-branes and its relationship to
the ADHM construction. It is well known that the D0-branes appear as instantons
in the D4-brane worldvolume. We add a Wilson line to the D4-brane in the guise
of an extended fundamental string and determine how this affects the D0-brane
dynamics. As the D0-brane moves in the presence of the Wilson line, it
experiences a Lorentz force, proportional to its Yang-Mills gauge connection.
From the perspective of the D0-brane quantum mechanics, this force emerges
through the ADHM construction of the self-dual gauge connection.
