The mother’s hands were shaking when she started writing on her 2-year-old’s body. They trembled so much that she couldn’t write correctly on her first try, even though the information was second nature: Her daughter’s name, Vira, along with her birth date and their family phone numbers.

“I thought that if my husband and I died, Vira could find who she is,” the mother, Oleksandra Makoviy, recalled…

A photo of Vira’s back that Ms. Makoviy shared on Instagram has been seen hundreds of thousands of times, after it was amplified by Ukrainian journalists and government officials. Messages of support poured in from people all over the world — many Ukrainian parents said they had taken similar action, and others turned the image into art honoring the country’s innocent on social media.

President Volodymyr Zelensky made a direct reference to efforts like Ms. Makoviy’s in a speech to the Spanish Parliament last week.