  We present optical and infrared observations taken with the Very Large
Telescope of the eclipsing binary pulsar system PSR B1718-19. The candidate
companion of the pulsar, identified earlier in Hubble Space Telescope
observations, has been detected in all three bands, R, I, and J. These
detections allowed us to derive constraints on temperature, radius, and mass,
pointing to a companion that has expanded to a radius between one of a main
sequence star and one at the Roche-limit. We focus on the role of tidal
circularisation in the system, which will have transformed the initially
eccentric orbit expected from formation scenarios into the nearly circular
orbit presently observed. Based on simple energy balance arguments, we are able
to draw a picture of the companion's evolution resulting from the energy
deposition in the star due to circularisation. In this picture, our measurement
of the companion's parameters is consistent with the expected initial
eccentricity. However, with the present understanding of tidal dissipation it
remains difficult to account for the short time in which the system was
circularised.
