There are a lot of things happening this month...
1 - New Year's Day according to the pre-Julian calendar
1 - The sacred fire in Vesta's temple was rekindled on this day
1 - KALENDS
1 - Women's festival of Matronalia --> During this festival Roman women would visit Juno's temple on the Esquiline. Their husbands would stay at home to pray, and give their wives money and other presents when the women returned home from the temple. Female household slaves were given a feast hosted by their mistress. During Matronalia the Vestal Virgins gave offerings of their hair to Juno Lucina in her sacred groves near Rome. Pregnant women would unbind their hair and clothing so as to prevent any restrictions that might carry over to their labour.
1 - Birthday of Mars Pater
5 - Navigum Isis --> This festival honored Isis as the patroness of sailing and the inventor of the sail. Traditionally this was the first day of the sailing season.
6 - Day honoring the gods of one's household
7 - NONES
7 - Junonalia --> This day honored Juno with a procession of 27 girls accompanying a statue of Juno carved out of a cypress tree.
7 - Festival for Vedovus
11 - Day sacred to Hercules
14 - Veturius Mamurius --> This festival was held to honor armor makers.
15 - IDES
15 - Festival of Attis and Cybele
15 - Day sacred to Anna Parenna and River Nymphs
15 - Julius Caesar was assassinated on this day ("Caesar, beware the IDES of March!")
15 - Guild Festival --> Guilds whose members practiced the arts of Minerva had a festival on this day. This was mainly a plebean festival, and was celebrated at Minerva's temple in Rome. Weapons used for war were purified during this festival.
16 - Festival of Bacchus begins --> This festival was held to honor Bacchus in order to convince the god to give a good grape harvest later that year. It was originally a Greek festival held to honor Dionysus.
17 - Festival of Bacchus ends
17 - Liberalia --> Liberala was a fertility festival celebrated in rural areas, and was held in honor of Liber Pater and Libera. Most towns created a large phallus and carted it through the countryside and into the town center where it stayed until the beginning of the next month. The phallus was decorated by a virtuous woman with flowers, which ensured a good crop at the next harvest. Masks were also hung on fences, and crude songs were sung during the procession.
19 - Quinquatrus --> "Fifth Day". Quinquatrus was the first day of the Qunquatria, and the traditional birthdate of Minerva. It took place on the 5th day after the Ides of March.
19 - Quinquatria begins --> The Quinquatria was a festival held to honor Mars and Minerva. The first day was called the Quinquatrus. It involved circus games and sacrifices to both deities.
22 - Procession of the Tree-Bearers
23 - Quinquatria ends
23 - Tubilustrium --> This was a ceremony held to purify the trumpet used in sacred rituals. During the ceremony, a ewe was sacrificed.
23 - Invocation day of Mars and Saturn
23 - Day of Mourning
24 - Dies Sanguinis
25 - Hilaria --> "Day of Joy" This festival honored Attis, and was primarily a festival for the followers of his cult. Several smaller festivals connected to the Hilaria were held on the preceeding days, such as the Dies Sanguinis ("day of blood") on March 24, and the Day of Mourning on March 23.
28 - Sacrifice at the Tombs --> This later festival was held later in the Empire to honor one's ancestors at their tomb.
30 - Festival of Janus and Concordia
31 - Festival for Luna