"No-one would have contemplated doing that unless they were married to someone who shared it," Captain Cochrane said.
Under the new guidelines, a requirement that Army officers only marry fellow officers - and only then with the approval of their headquarters - will be abolished.
The new code is being drawn up in an attempt to reverse a slump in recruitment across the world.
Speaking on BBC Radio 4's Today programme, Captain Bill Cochrane said: "Historically this is a major step forward".
Life on the road
While change may be hard for some, he said, it was necessary to reassess how the Army operated.
"When the Salvation Army began, missionaries were moving around the country, moving from town to town, from village to village, starting Salvation Army work, staying for a few weeks, a few months.
"No-one would have contemplated doing that unless they were married to someone who shared it," Captain Cochrane said.
"But we have to face the context in which we're working today and clearly that's changed."
The proposed changes were drawn up by the previous General of the Salvation Army, Paul Rader.
Some 25,000 officers around the world were asked to comment.
The overwhelming view was that the change was necessary, said Captain Cochrane.
The recommendations will now be left to individual headquarters to adopt if they wish.
History of service
The Salvation Army was founded in 1865, in the East End of London, by Methodist minister William Booth.
Mr Booth wanted to offer practical help to the poor and destitute, as well as preaching the Gospel to them.
The organisation was originally called the Christian Mission, but changed its name to the Salvation Army in 1878.
Internationally, the Salvation Army operates in 107 countries and its charitable work is well recognised.
Its work includes offering care to the elderly, offenders, drug addicts, blind and handicapped people, providing shelter for the homeless and operating about 2,000 food distribution centres.