The "now I am a bachelor, I live with my son" version surely has the chorus "the foggy, foggy dew" - or so it was always sung in my family.
The "down the glen one Easter morn" version about the Easter Rising of 1916 is slightly inaccurate; the weather was unseasonably beautiful that week, to the extent that for decades heatwaves were known as "rebellion weather". No fog then; though immediately the Rising was over the rain came pouring down and the temperature plummeted, and it remained pretty awful for the next year or more.