What do Quakers believe about war and serving in the military?

I am a Quaker son of Quaker parents, and both my father and I served in the U.S. military. Reconciling a belief in pacifism with service in an armed force is, like many other decisions, a question which can only be answered by the individual upon communing with the Light Within. My father served three years in the Air Force because there was a draft and he chose not to exempt himself for reasons which only he understood. When I made my choice to join the military, my father expressed concern and asked me questions, but said that ultimately the choice was mine. I would say that the choice to be a member of the armed forces, and the choices which subsequently present themselves, are a matter for the individual and the Wisdom and Divine Will that guides them. One of the reasons that community is so important for Quakers is that listening for and following the Divine Will is not always easy. Important choices deserve worshipful support and help.

Pacifism was huge in traditional Quakerism, to the point that their home countries (particularly England, where they started) would often get a bit angry with the Quakers for failing to participate in their wars.

However, over time, Quakerism as a whole has gotten much more liberal (relative to their starting-point, mind you), and it has become increasingly common for Quakers to join the military. Initially, their involvement was medical, but later expanded into combat. In doctrine, I think most Quaker churches still prefer pacifism, but it is not stressed nearly as much as it used to be.

The Biblical basis for their belief is a mixture of Matthew 5:9 ("Blessed are the peace-makers"), Matt 5:38-39 ("Turn the other cheek", although this is less military-related), and perhaps Matt 24:6-8 ("Wars and rumours of wars").

But their support comes mostly from the broad and very common theme throughout Scripture that all life is valuable, and we should love our neighbors and enemies. With these principles in mind, and a few steps of logic, they also have support from a few more ideas: that to take someone's life is to take away their chance to turn to God, that humans bear the image of God, that we should be more concerned with evangelizing and doing good works than the petty conflicts our governments get into, etc.

I am a Quaker, and as such am regarded in our denomination as a voluntary minister. Quakers do not have any laid down doctrines, creeds, or rules which we must follow. The majority of Quakers do not believe in violence of any kind for any reason. A basic Quaker belief, which was quoted above, is that there is "that of God within everyone", and therefore if we kill another person or commit violence against them we are doing that to God, which is completely unacceptable. If you want a source for this, you can find it in "Quaker Faith and Practice", which is the closest Quakers come to having a book of "doctrine and rules" even though it is actually neither doctrinal nor rule based and it is up to each individual Quaker to decide for himself or herself whether or not to follow or believe in anything written in that book.

Quakers are considered one of the "peace churches" who oppose war of any kind, and typically refuse to participate in it. However they are also not a denomination which expects everyone in it to do exactly what the church says. See this article for more information. The biblical basis for pacifism is discussed here.

I believe that some Quakers have indeed served in the military as medics. I've never heard of one serving as a chaplain.

In the Bible one of the 10 Commandments says "Thou Shalt Not Kill". However the belief is based on many other references too. Quakers also refuse to swear oaths, on the basis that they always tell the truth and will not swear in God's name or any other.

The Quakers formed unarmed pacifist units to supply relief to refugees and ambulances to drive in battle zones picking up the wounded in WW2. 3 of my family served in these units. The Quakers were awarded the Nobel Peace Prize in 1947 for this work. Some more background information can be found at this link: http://www.nobelprize.org/nobel_prizes/peace/laureates/1947/press.html

Here is a memorial recently erected to their pacifism and relief work during WW2: http://www.theguardian.com/society/2013/apr/16/rare-memorial-inspires-quakers-work