Sunderland s head coach took his players north of the border for a week ahead of the 2-0 win over Hearts of Midlothian at Tynecastle.
While Johnson admits the club still have a 'lot of work' to do in the transfer market to complete their squad, the head coach has begun his preparations with a number of players who will have a key part to play in the push for promotion this season.
The squad is also currently being supplemented by a number of young players hoping to make their senior breakthrough.
Johnson oversaw a number of initiatives during the week that he hopes will bring the group closer together.
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"We worked a little bit with a guy from the Special Forces," Johnson said.
"I don't want to reveal too much about that, but that was quite interesting.
"There were some bonding games that were quite funny, and that got a few in the group to come out of their shell a little bit.
"We also asked Rob [Mason] the club historian to speak to us. That was important to me.
"It wasn't so much to learn about the club so much as to learn more about the people, for him to articulate the history of Sunderland and its people.
"It was really interesting in terms of their mindset, what they expect, the kind of character that they want to see on the pitch, and where that passion comes from."
Sunderland are stepping up their preparations with a pre-season friendly at York City on Wednesday evening, with Johnson eager to secure reinforcements in the coming days and weeks.
"We had a nice balance in Edinburgh," he said.
"They worked extremely hard, but what we haven't done is a lot of tactical work - there's no point, really, because most of the players were here already and have that understanding of what we're trying to do.
"We need to bring in at least one more centre-half, and two full-backs if not three.
"So that back line could be anything at the moment, depending on what happens."