Mars in Libra (8/6 – 9/22) is an odd bird of a placement. Mars is about asserting the self, but in Libra it needs others to do so.
We often see this placement in the natal charts of those who work with one-to-one relationships — marriage counselors, moderators of debates — or who find themselves in the middle when their friends are fighting.
The Mars-in-Libra native may be conflict-phobic, and/or they may be an expert at conflict resolution. A lot of lawyers have this placement.
The planet of ego in the sign of other-orientation is an inherent paradox, one that all of us will be confronting over the weeks ahead. How does the self express its individuality while joined at the hip to the not-self?
Significant others
Mars always wants to exert, to show strength. Libra’s genius is finding balance. Together they constitute a lesson about negotiating compromises, finding quid-pro-quos, resolving antagonisms. If the transit is prominent in your chart (check your houses for the first degrees of cardinal signs), you may find yourself in unbalanced situations that force you to step in. Inequality calls out for your leadership.
Ultimately, the balance that the soul seeks is between who we are as an individual, vs. who we are when we engage with others. It’s an age-old dilemma, and it pays the bills of many a psychotherapist.
It’s also a hot topic in many an astrology session. Clients hope the astrologer can help them understand their partner — current or future, actual or fantasized. There’s a lot of curiosity around the question Who’s the source of the problems I’m having: me or him? 
There’s somebody else in my chart
Strangely, there’s far less curiosity about how astrology could actually address this. People want to know how they can get their desires met from a person who isn’t them, but seldom consider the implications of the question: that their own birth chart could possibly say something about other people in their life.
Relationships aren’t the only area of life that invites this knotty question, of course. At issue is the whole mystery of how astrology works. How can this circle of arcane symbols know such things? Clients may have vaguely heard of the Law of Correspondences, synchronicity, As-Above-So-Below, and other opaque catchphrases, but mostly only care about whether the system works.
No harm in that. The operational principles behind astrology are tricky to explain, as they they violate conventional assumptions about reality, and they are beyond the reach of this essay. But the short answer is that astrology works by mirroring. The reason we can infer from your chart who you’re likely to attract is because we can see what your soul wants you to learn about relating, socializing and cooperation.
Other people are personifications of these lessons. Although “There’s nobody in the chart but you” (Rob Hand), there are plenty of clues about alter-egos: “other selves.” For those interested in going a little deeper into the mystery of relationship, this Mars-in-Libra period can provide a rich study.
Consider those you attract — either in affection or antipathy — as mirrored selves. They are facets of your psyche that you can’t see alone.
Sparring partners
The sign Libra is not, contrary to popular opinion, about romance. It’s about dovetailing. Two halves come together to make a whole; sometimes in affection, and at other times — especially since this is a Mars transit — in competition.
We magnetize people, but not in the Venusian sense. The transit has nothing to say about whether we like the person. It sets up situations where we magnetize a Martial counterpart, with whom we get to flex our muscles: maybe a sparring partner, or a teammate who helps us get things done.
Keep this in mind when the transit clicks into an exact opposition with the Saturn-Neptune conjunction (8/7-11). The self-other paradox will be showing up everywhere.
Around the Full Moon (8/17), it’ll become obvious how much or little we’ve learned.
