According to Donella Meadows in her ground breaking work, Thinking in Systems, a A primer, every system has a purpose or chief function. the system produces something of value, an intended results.

Capt. William Swenson
In a conversation with Colonel Marc Gauthier, a 34 year veteran of the United States Army, Army Ranger and Special Forces, I asked: what is the primary function or purpose of the leadership system for the Army? After some clarification, he thought for a moment and referenced General Mark A Milley, current General of the Army, the highest ranking officer and CEO equivalent of the Army.
On August 7, 2015 General Milley accepted the appointment and outlined his priorities. The first two might be expected from an Army General:
1) Readiness; and
2) Innovate.
However, the third priority is different. Here is the full text of his communication to his troops about this third priority
Care of the Troops: (Always) Every day we must keep foremost in our minds our Soldiers, Civilians, and their Families. Our collective strength depends on our people—their mental and physical resilience is at our core. We must always treat each other with respect and lead with integrity. Our Soldiers are the crown jewels of the Nation; we must love them, protect them, and always keep faith with them.
A system purpose can be tangible like the circulatory system pumping blood and delivering nutrients, gas, and hormones to the body. It can also be intangible like a leader serving her subordinates. This purpose or function is the “why” leadership exists. It is the reason why a leader gets up on the morning. It is the way individual leaders see themselves delivering maximum value to customers and stakeholders. General Milley was simply restating what every commissioned and enlisted officer knows from the first day of training – the job of a leader
is to love his men (and women), it is to care for them, and always keep faith with them.
On October 14, 2013, Captain William Swenson received the nations highest honor – the Medal Of Honor. This is his story, of how he fulfilled General Milley’s priority – of loving a soldier.