The position, and the line behind it
Measured at noon from 1930 to 2035, the Sun on 11 March falls between about 20.0 and 21.4 degrees of Pisces. The lower end touches the decan boundary exactly, which means an early hour in a low year could still leave the Sun a fraction short of it.
For almost every birth on this date, though, the Sun has cleared twenty degrees and entered the third and last face of Pisces. If you want certainty rather than almost, the widget above computes the longitude for your own year, hour and place.
The width of that range comes from the leap cycle rather than from anything irregular. The date creeps later against the orbit by about six hours a year and February the twenty ninth pulls it back, so a century of birthdays lands inside a band a degree and a half wide.
Mars from both directions
The Chaldean order runs its seven planets in a loop from zero degrees of Aries, and because seven does not divide evenly into thirty six the sequence closes on Mars, the planet it opened with. The last face of Pisces is that closing decan.
The triplicity scheme arrives at the same planet by different reasoning. It gives a sign's faces to the signs of its element in order, and a Pisces sequence runs Pisces, Cancer, Scorpio. The final face therefore belongs to Scorpio, which traditional astrology also assigns to Mars. Agreement between the schemes is uncommon and this is one of the places it happens.
What tradition makes of the closing decan
Older texts treat the end of Pisces as the end of the whole circle, immediately before the equinox restarts it at zero Aries. Mars over water is read as directed rather than diffuse, and this face is usually described as the most decisive part of an otherwise yielding sign.
That is the tradition's reading of a band of longitude and it is marked as such. It is not a personality the date hands out, and nothing on this page predicts anything about a life.
The same texts are careful to attach these readings to the band of longitude, not to the person. A face colours whatever planet occupies it, and a Sun there is read as taking on that colour rather than as being defined by it.
The date is not the chart
The sun sign here is beyond argument, since the equinox is still more than a week off. What remains open is nearly everything else. The Moon travels about thirteen degrees a day and can land in either of two signs depending on the hour of birth.
The rising sign is entirely a function of clock time and place, and any of the twelve can be on the horizon on 11 March. Anyone who tells you the date alone describes a person is skipping the parts that actually vary.
The widget above will give you the solar degree, the face it falls in and the distance to the nearest sign boundary. That is the checkable part. Everything after it, including anything on this page about what Mars is read as adding, is interpretation and is marked as interpretation.
Questions people ask about this
Is 11 March in the second or third decan of Pisces?
The third in all but the earliest cases. The Sun ranges from about twenty to twenty one and a half degrees, and the boundary is twenty, so only a birth right at the low end of that range would fall short.
Who rules the third decan of Pisces?
Mars, under both schemes. The Chaldean sequence ends on it, and the triplicity scheme reaches it through Scorpio, which traditional astrology also gives to Mars.
Is this the last decan of the zodiac?
Yes. Pisces is the final sign and this is its final face, ending at the equinox where zero degrees of Aries begins the count again.
Could an 11 March birth ever be Aries?
No. The equinox falls around 20 March, so this date is comfortably inside Pisces in every year on record.
How precise does my birth time need to be?
For the sun sign, not at all. For the decan on this date, an approximate hour is enough in most years. For the Moon and the rising sign, the more precise the better.
Why do two sources give my decan different rulers?
Because many popular articles use the triplicity scheme without saying so while others use the Chaldean order. Here the two happen to agree, but across the thirty six faces they often do not.