The first Mother's Day was a call for peace.

From Sojourners website:

Did you know that Mother's Day was suggested as a day of peace in the United States by Julia Ward Howe who protested the carnage of war in her bold proclamation of 1870? Decades later in 1907, the first Mother's Day observance was held at a church service honoring the memory of Anna Reese Jarvis in Grafton, West Virginia. Jarvis, an Appalachian homemaker, organized women during the Civil War to work for better sanitary conditions and to reconcile Union and Confederate neighbors.

Mother's Day Proclamation
-- Julia Ward Howe, 1870

Arise all women who have hearts, whether your baptism be that of water or of tears! Say firmly: "We will not have great questions decided by irrelevant agencies, our husbands shall not come to us, reeking with carnage, for caresses and applause. Our sons shall not be taken from us to unlearn all that we have been able to teach them of charity, mercy and patience. We women of one country will be too tender of those of another country to allow our sons to be trained to injure theirs."

From the bosom of the devastated earth a voice goes up with our own. It says "Disarm, disarm! The Sword of murder is not the balance of justice." Blood does not wipe out dishonor nor violence indicate possession.

As men have often forsaken the plow and the anvil at the summons of war, let women now leave all that may be left of home for a great and earnest day of counsel. Let them meet first, as women, to bewail and commemorate the dead. Let them then solemnly take counsel with each other as to the means whereby the great human family can live in peace, each learning after his own time, the sacred impress, not of Caesar, but of God.

In the name of womanhood and of humanity, I earnestly ask that a general congress of women without limit of nationality may be appointed and held at some place deemed most convenient and at the earliest period consistent with its objects, to promote the alliance of the different nationalities, the amicable settlement of international questions, the great and general interests of peace.