According to Manilius, the planet Mars  is ardent, and presides over the genitals. Called "The Bringer Of War" in Alan Leo's What is a Horoscope? because the planet is associated with the Roman god of war Mars. In Western astrology, Mars is associated with confident and aggressive personalities. It is also associated with the principles of energy, ambition and drive.

Mars is considered the ruling planet of Aries. Before the discovery of the planet Pluto, it was also considered the ruler of Scorpio. Most modern astrologers consider Pluto the ruler of Scorpio, but may regard Mars as a co-ruler, while some more traditional astrologers still regard Mars as the only ruler of Scorpio.

Mars is associated with Tuesday. Dante Alighieri associated Mars with the liberal art of arithmetic.

In Chinese astrology, Mars is ruled by the element fire. In Indian astrology, Mars is called Mangala

The Mars first house placement intensifies the assertiveness of the personality type described by your Ascendant. With any Ascendant, Mars in the first house increases the vitality, and produces a somewhat more assertive, more outgoing, and more energetic individual.
 
Your appearance is likely to be robust and muscular and you may be stronger that other members of your family of the same sex. You are always one to be directly involved in affairs; never an idle bystander. This element produces drive and creates more ambition and the aptitude for hard work, with a competitive drive for recognition and acclaim.
 
This position is usually considered, by traditionalists, to be more desirable for men than for women, because it displays the assertive characteristics associated with males. Females with this placement often have the self-confidence and competitive traits to enter and succeed in male dominated professions.

The Mars second house placement suggests that energies are spent in the pursuit of material and financial gains, and in this regard you are very resourceful. You have a strong drive to earn money and an equally strong compulsion to spend it. Mars in the second house poses the necessity to learn careful budgeting and proper handling of money, and neither are apt to be natural traits. You are competitive in finance and business, and you may be well qualified and inclined toward owning your own business. You are not afraid of taking a risk to meet your financial goals. In a business sense, you are a very competitive person.

The Mars third house placement denotes an aggressive, active intellect. You are quick thinking and resourceful, but you sometimes jump to conclusions a little too quickly. Your speech is direct and sharp. You are apt to get into arguments with family members, and when you do, you are not the least bit shy about pointing out their personal deficiencies. You are always rushed. You drive too fast, and you're a little too impatient when caught in traffic. In matters of the mind, you are highly competitive.

The Mars fourth house placement shows energies expended in the home and the domestic scene. You have an aggressive drive for security, and you may have a strong sense of patriotism. This placement usually shows many family quarrels and squabbles, and often persons with this placement of Mars choose not to marry. This is also the placement for the active do-it-yourself repairman, always busy fixing up or improving the home. As this placement is also connected to the land, there may be interests in environmental and ecological movements, perhaps expressed in an active or militant manner. Physically, this position is rewarding, because you are likely to retain a strong constitution, even into old age.