Bhai Ghanaiya Ji carried water on the battlefield at Anandpur and gave it to the wounded of both sides. He was reported to the Guru for reviving enemy soldiers.
Asked to explain himself he said he saw no Mughals and no Sikhs, only the Guru's face in every man. Guru Gobind Singh Ji gave him ointment as well as water and told him to dress the wounds too.
He founded the Sevapanthi order, which took up seva as its whole practice, ran dispensaries and rest houses, and produced a body of Punjabi devotional writing. Sevapanthi deras existed across the Punjab and a number survive.
He was from Sodhara near Wazirabad, in what is now Pakistan.
The episode is quoted whenever the ethics of the Sikh martial tradition are argued about, and it is quoted correctly, because the instruction was not to stop but to do more.
The complaint against him was that he was reviving enemy soldiers who would fight again. The answer he was given was ointment, to use as well as the water.
The Sevapanthi writers, Bhai Addan Shah and the line after him, produced commentaries and vaars in Punjabi that sit outside the mainstream Sikh canon and are almost entirely unpublished.
The comparison with the Red Cross is made constantly and is anachronistic. What the episode establishes is a rule about who counts as a person in a fight, stated in the middle of one.