There are several reforms in military practice and procedure which have been attributed to Marius. Many of these reforms were not immediate changes that can be pinned to a single date, but rather processes set into motion by Marius' predecessors which came to fruition when Marius implemented the changes within his army. Marius' two major reforms which can be classified as such processes were the structural changes made to the cohorts and the change in the land requirement previously necessary for service. Marius is also credited with some tactical adaptations, as well as the expansion of some traditions, which helped to make the army more efficient.
Adjustment of the heavy pilum (javelin):
According to Plutarch, Marius replaced one of the two iron rivets which held the spearhead to the pilum's shaft with a wooden rivet. With this decrease in strength, the point would break off upon impact. This made it impossible for the enemy to return the weapon against the Romans. Caesar later moved away from this adaptation; instead choosing to leave the iron beneath the point untempered, so that it would bend on impact and be impossible to return.
Transport of all necessary equipment by soldiers:
Instead of carrying equipment on carts and mules, which slowed the army down to the pace of the baggage train, Marius made his men carry their supplies. A soldiers gear, aside from the armor they wore and the weapons they carried, also included emergency rations as well as entrenching and cooking tools. Josephus contends that a regular soldier would have to carry their weapons, a saw, a wicker basket for shifting earth, a piece of rope or leather, a sickle, and a pickax with a cutting blade on one side and a tine on the other for digging or cutting. The items they couldn't carry on their person would be attached onto a large pole, or pila muralia. Marius supposedly introduced the fork on the head of the pole for facilitated packing up and carrying of equipment. Plutarch writes in Marius' biography that the soldiers were nicknamed Marius' Mules, laden down with the baggage of the army. This epithet and the accompanying image would characterize the Roman Army throughout the time of the Empire.
Employment of the uniform Eagle standard (Aquila) for each legion:
The Republican legion, according to Pliny the Elder, had five standards: eagle, wolf, minotaur, horse, and boar. Each of these animals were associated with the different divisions hastati, principes and triarii; which were divisions based on wealth and equipment. The selection of the Eagle or Aquila, a bird associated with Jupiter, as the supreme standard of all legions was Marius' doing. The soldiers gave devotions to their Eagle standard which symbolized their collective spirit. The standard was carried into war by a senior standard-bearer, the aquilifer, second only to a centurion in rank. It not only worked to increase the loyalty and devotion of soldiers to the unit and commander; but, it is also reflective of the merging of the old class divisions within the army facilitated by the increased use of the Cohort.