The third column shows 2nd so perhaps this refers to writings further up the page.
If he was convicted and imprisoned whilst on leave then the 'Leave 18.11.11' would be his last day of official leave and the next day, as he was unable to rejoin his unit, would perhaps be the first day of his desertion.
The writing at the bottom in red shows the info, presumably about being convicted by civil powers, is dated 18.3.12 hence his discharge from the Army on 21.3.12. Perhaps he was often in trouble in the Army and they decided to discharge him. Which would explain why he later joined the Navy using his uncle's name.
Jean