Below is a breakdown of the ASP.NET master page event order in relation to the event order of the content page that is using the master page.
Content Page | Master Page | |
| 1 | PreInit | |
| 2 | Controls Init | |
| 3 | Controls Init | |
| 4 | Init | |
| 5 | Init | |
| 6 | Load | |
| 7 | Load | |
| 8 | Controls Load | |
| 9 | Controls Load | |
| 10 | PreRender | |
| 11 | PreRender | |
| 12 | Controls PreRender | |
| 13 | Controls PreRender | |
| 14 | Controls Unload | |
| 15 | Controls Unload | |
| 16 | Unload | |
| 17 | Unload |
Information taken from https://msdn.microsoft.com/en-us/library/dct97kc3.aspx