Mars is the warrior planet. Heat, passion and action are the traits associated with the red planet of impulse. When the Mars energy goes into battle through a 12th house transit our karmic and unconscious fights ensue.
The 12th house is the house of the unseen. It is a deeply Spiritual part of the birth chart. Retreats, seclusion, institutions, anonymity, secrets and sacrifice are the shadows that dwell there. All that is imprinted on your soul from before this incarnation swim around in the unconsciousness of the 12th house. It is the house of self undoing and secret foes because of our own illusions, delusions & karmic debt.
Mars transit of the 12th house is a challenging time. The planet and house are not comfortable together. Mars takes approx. 2 years to transit a chart so will spend approx. 2months in a house. Patience with a challenging transit is definitely not one of Mars's strong suits.
Mars is at the start of my 12th house transit. Basically it will be about fighting my hidden fears. I currently have Saturn, the heavy duty task master, in transit through my 12th house also. Saturn has been plodding through here for over 2 years and not due to leave any time soon. I am about to put my hard earned lessons to the test. But wait there's more. I also have my Natal Neptune in its house of rulership in the 12th. Neptune makes hard natal aspects to Saturn, Venus and my MC/IC axis. Then there is my natal Moon conjunct the Ascendant from the 12th house who makes hard aspects natally to Uranus and Pluto.
I see Mars as the trailblazer who will ignite my hard natal aspects, overtaking Saturn and burning with courage and energy to clear a pathway through. My dreams may become my torches to guide and light my way. My Spiritual faith may fire up my soul with courage. Strategic actions behind the scenes may slay my dragons. Acting on our out my fears may burn me. Impulsively embracing shady deals or characters, pie in the sky dreams or occult dabbling without armour could inflame delusions and harm me mentally and or physically. Acting on my psychic intuitions will be my battle weapon.
Working hard in solitude, planting the seeds in the womb of the unseen for the time Mars crosses over into my 1st house will be using this transit in a positive way.
I am foreseeing dealings with hospitals (12th house) medications/anaesthetics/(Neptune) accident, injury or surgery/surgeon (Mars), parents (MC/IC axis), bones, knees, restriction, responsibility (Saturn), family, fluid, emotion (Moon) unexpected, restructuring(Uranus & Pluto).
Of course deeper issues for me will be brought up by any occurences that involve the above themes. Loneliness, isolation, dependence, restructuring of responsibility etc will require inner Spiritual faith to battle on.
