Systems Alliance Navy (SAN)
Active:	23 September 2149 CE - 31 December 2191 CE
Organization:	Systems Alliance Armed Forces
Affiliation:	Systems Alliance
Type:	Navy
Role:	Space control Naval warfare Stellarlift Power projection Deterrence Stellar security
Size:	9.1 million (regular) 900,000 (reserves) 3,200 ships 120,000 aircraft
Part of:	Systems Alliance Naval Command
Headquarters:	Sydney, Australia (2149 CE - 2162 CE) Arcturus Station (2162 CE - 2186 CE) London, England (2186 CE - 2191 CE)
Motto:	"Through hardships to the stars." (English translation)
Colors:	Navy blue and black
Engagements:	First Contact War Skyllian Blitz Operation Gyrfalcon Theshaca Raids Eden Prime War Counter-piracy campaign of 2184 CE Reaper War
Commanders:	Flt Adm. Steven Hackett (last)

"Per aspera ad astra."

— SAN motto.

The Systems Alliance Navy (SAN), also known as simply the Alliance Navy and as the Human Navy to aliens, was the naval service branch of the Systems Alliance Armed Forces, and one of the four uniformed services of the Systems Alliance. Established only a month after the signing of the Charter, the Alliance Navy became the very first branch of the Alliance military, with an obvious focus on establishing a single human navy from which to begin humanity's expansion into Sol and beyond. The Navy's initial size was limited to three fleets, each tasked with escort, colonial protection and national security: this initial fighting force was comprised of very early Alliance warship designs, most of which soon proved to be inadequate when the Alliance was thrust into war with an alien species in 2157 CE. After the First Contact War, two more fleets were activated, shipbuilding was expanded and accelerated, and the process of modernizing the Alliance Navy to make it a worthwhile naval force on the galactic scene took place. By 2170 CE, the Navy's total strength was brought up to eight fleets, each outfitted with second and, although in minority, third generation warships, with the Navy also having access to various other military installations from which to project its power. In just under thirty years, the Alliance Navy had become a powerful force to be reckoned with, proving its superiority in both the Skyllian Blitz and Eden Prime War, against the batarians and geth respectively. As the Alliance Navy's role continued to grow, especially following humanity's acceptance of Council powers and responsibilities after the Battle of the Citadel in 2183 CE: the Alliance Navy was also unique in its exclusive deployment of carriers, a ship class which the other races were unfamiliar with and had proved its superiority during the First Contact War and in the other conflicts succeeding it. Access to these ships, and the Alliance Navy's expert use of them, elevated them to become of the most powerful and respected navies in the entire galaxy. While nowhere near as large as the colossal and mighty Turian Navy, the Alliance Navy proved it was a force to be feared in war.

The Alliance Navy saw extensive action throughout the First Contact War, Skyllian Blitz, Operation Gyrfalcon, Theshaca Raids, Eden Prime War, the Counter-piracy campaign of 2184 CE and the Reaper War. The Alliance Navy was dealt a significant blow in the opening 24 hours of the Reaper War, known historically as Reaper Day, with an entire fleet obliterated, two more reduced to half strength each, and the rest forced to abandon their positions, a result that ultimately lead to the fall and occupation of humanity's homeworld, Earth, as well as the destruction of Arcturus Station and the deaths of the entire Alliance government, leading to a bitter and humiliating defeat for the Alliance Navy, shattering the illusion of its invincibility that had been promoted in the wars before. The Alliance Navy would regroup after these defeats however and would eventually secure vengeance for Reaper Day on 24 September 2186 CE, when it participated in a massive pan-galactic military alliance to deliver the Crucible to Earth, where it destroyed the Reapers once and for all, ending the war, but not before the Alliance Navy suffered even more casualties, being reduced to half of its original strength and its command structure decimated. The Alliance Navy struggled to recover after the war, largely due a focus on reconstruction efforts and rebuilding the Alliance government. With the dissolution of the Alliance in 2191 CE, the Alliance Navy was reorganized into the Systems Coalition Navy.