Mars in the 3rd house (Sahaja, the house of courage) brings the significations of Mars, namely energy & courage, younger siblings, land & property, into the area of courage, self-effort, siblings and communication. The 3rd house governs courage & effort, younger siblings, communication & skills, short journeys.
Results of Mars in the 3rd House
Mars is a malefic planet, so here it tends to bring anger, impulsiveness, accidents, conflict and disputes over property focused on courage, self-effort, siblings and communication.The exact result depends on which sign Mars occupies here and the aspects it receives.
When It Activates
These results typically surface during the Vimshottari mahadasha or antardasha of Mars, and when transiting planets trigger the 3rd house. A well-placed Mars here supports bravery, initiative, talent and good bonds with siblings; when afflicted it can indicate timidity, lack of drive and strained sibling relationships.