With Mars in Libra the persons energies are directed towards the realm of human relationships and justice between people. They may be very placid in some ares but when it comes to injustice between people their strength will be activated and aroused. Libra is the sign of the scales and it constantly tries to evaluate what is right and wrong and where true balance lies. When combined with Mars the planet of energy and drive it leads to a nature that is facinated by the sphere of human interaction. Mars actually is considered in detriment in this sign as Libra is opposite to the sign of Aries which Mars naturally rules. Possibly this is due to the fact that the naturally uninhibited Martian energy is now constrained by the more refined nature of Libra. In extreme circumstances the normally placid Libran nature which supresses conflict will break down and the martian energy will be let loose and break forth in a major confrontation. As explained above this is likely to be when the person has seen enough injustice and can supress their anger no longer.