Maguire is still waiting for a retrial after being found guilty of charges including bodily harm and attempted bribery while on holiday in Mykonos in the summer.
That conviction has been nullified while he awaits a new hearing – but he has spoken of the distress the episode caused.
Southgate said: “With Harry, I was really pleased. I felt that the red card here could bottom everything out.
“You could see on his face when he was walking off the pitch that night how he was just having one of those spells where he must have felt everything was against him.
“I had some good conversations with him and I know his club would have supported him and his club performances were solid after that and I thought it was important to get him back in an England shirt.
“It was lovely moment for him to captain the team and to get the goal as well is a real boost so that was great to see.”
Maguire is suspended for England’s game against Belgium on Sunday, while Southgate is without Joe Gomez, who underwent knee surgery this week and Conor Coady, who has to self-isolate following contact with someone who has tested positive for Covid-19.
It leaves England’s defensive options are wearing thin and Southgate says he is considering options ahead of the Euros.
“We have been very pleased with the players that are with us now,” he said. “I talked a little bit about Conor and the impact he has had, but there are some other good centre-backs in the league and we are always monitoring and assessing what the batting order should be.
“There’s a lot of good players around. We have to keep looking. We are in this very worrying situation on player welfare where at best players are picking up minor muscle injuries and at worst there is the danger of more serious injuries. That is a concern.
“So we have to keep looking at every position and we just don’t know what’s going to happen in the next few months.”
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