Mangala Trayodashi or Shukla
Trayodashi is the name for the 13th Tithi (lunar day). Its nature is Jaya Prada, which can be interpreted as
"one that brings victory". It's good for following works: Alankar,
Pratishta, marriage, travelling, house-warming, purchasing clothes, war, etc.,
all auspicious works except Upanayana.
According to most classical texts
(Muhurta Chintamani, Poorva Kalamrita, Brihat Samhita, Vasishta Samhita etc.)
Kama is Devata which rules Trayodashi, who's is responsible for forming
friendships, sensual pleasures and gratification, sexual desire and its
fulfillment. Kamadeva is also responsible for human's desires, wishes,
passions, pleasure of the senses, the aesthetic enjoyment of life, affection,
love, etc.
Being Jaya (that can be translated as "victory", "advancement") and ruled by Mangala (Mars), 13th Tithi is suitable for following works: war, weapon making, training in army, collection of army, actions or matters related to power / strength, travelling, festival, medicine, trades, houses, flags & conch-shell.