From corpsman to infantryman, submariner to special operator, Navy Secretary Ray Mabus has insisted that every Navy and Marine Corps job be opened to qualified women. It allows women to compete on a more equal footing with men, it recruits a much larger portion of the nation's workforce and graduates, and he's argued, it's only fair.

Many of these moves have come over strenuous and strident opposition.

The first was the undersea fleet. Mabus came into office in 2009 and aggressively pushed to open it to women.

"I believe women should have every opportunity to serve at sea, and that includes aboard submarines," Mabus told Navy Times at the time. The proposal had objections. Berthing changes would be expensive and take some time. Privacy issues would be difficult in a sub's cramped spaces. Submarine wives were among the biggest opponents.

"There is no way they will be able to stop fraternization," one wife told Navy Times in 2009. "I will never be at ease."

The integration effort moved ahead and the first women officers reported to the sub fleet in late 2011. The first enlisted women are set to report to the force this year.

When the Defense Department announced in 2013 its intention to open all roles to women in 2016, the Navy Department was already well on its way, Mabus said. In addition to subs, Submarines were opened to women in 2011, and in 2014, the Coastal Riverine Force began deploying women in 2014. The last step came late in 2015, when Navy officials announced they open the SEALs to women who could survive their arduous training.

The biggest controversy has came from the Marine Corps, whose leaders recommended to Mabus that ground combat units like infantry and reconnaissance remain male-only and cited a lengthy study that found women underperformed in these units and were who conducted a gender integration study leading up to the final decision. Information released by the corps found that women underperformed in ground combat tasks and were more likely to be injured or hamperbring down their teams.

Then-Commandant Gen. Joseph Dunford recommended that women remain banned from some infantry and reconnaissance jobs, officials told Marine Corps Times, but Mabus was unswayed.

In an interview with NPR, he decried the study as flawed.

"It started out with a fairly large component of the men thinking 'this is not a good idea,' and 'women will never be able to do this,' " he told host David Greene. "When you start out with that mindset, you're almost presupposing the outcome."

Many Marines took issue with Mabus' comments. An influential sergeant major who oversaw the study said Mabus was "way off base" and a retired 3-star wrote an op-ed criticizing the move.

In the end, Mabus' decision prevailed, and on Dec. 3, Defense Secretary Ash Carter announced that all four services would be opening every job specialty to women: No exceptions.

It was Mabus’ latest clash with the Marine Corps. The tradition-bound service has also stymied Mabus on some of his personnel reforms, like expanding opportunities for taking three years off and career flexibility. , though many of his most innovative initiatives were not adopted by the service, including the career path flexibility and fitness updates announced in 2015. Marine officials, however, have contended that Mabus announced these reform proposals before consulting them.

One push they have been forced to get on board with is Mabus' push for gender neutral uniforms. This drive is  is a uniform change, based on an oft-repeated Mabus line that sailors and Marines should look like sailors and Marines, not female sailors and male sailors, or female Marines and male Marines. The idea came from was borne of Mabus’ first Army-Navy game in 2009, he told Navy Times, when he watched Army cadets and Navy midshipmen march onto the field for the first time close-up.

"The cadets marched out in absolutely gender-neutral uniforms. Mids marched out and you could tell what the women wore by their covers," he recalled. "If we ask another group to wear a different uniform, can you imagine the trouble we'd get in?"

For instance, men and women with the New York Police Department wear the same style of dress uniform.

Mabus is pushing to outfit men and women in the same style uniforms and symbolically break down barriers that have stood for decades.

"They're an historical accident because women couldn't join the Navy or the Marine Corps," he said. "They joined the auxiliary, and they were given different uniforms to indicate that they weren't full sailors or Marines."

The push has had its own controversies. While the Navy has adopted mandarin collars and combination covers for female officers and designed junior enlisted "crackerjack" dress blues for women, the Marine Corps has been slower to get on board. In late 2013, word leaked that a small board was considering a new cover for all Marines, modeled off of the historical "Dan Daly" cap worn in the early 20th century.

Trouble was, that cover looks a lot like the modern women's cover, and Marines decried the suggestion as a "girlie hat."

Mabus argued that wearing separate uniforms — the men in the iconic officer whites or Marine enlisted blues — and the women in another uniform creates an unconscious bias, where there are sailors and women sailors, or Marines and women Marines.

"It's not an arbitrary thing. It's not just, I woke up one morning and this is what I decided," he said. "There are reasons to do this, and whether conscious or unconscious bias, whether just viewing women differently as sailors because, if women are qualified to meet any of the standards and any of the occupations, why should we treat them differently?"

The latest flash point is over Marine Corps boot camp. Mabus has ordered the service to plan to make their historically gender-segregated boot camp co-ed, but sources told Marine Corps Times on Friday that it's unlikely that Marine boot camp will be go fully co-ed but are looking at ways to integrate more of the training. Instead, Marine Corps officials could look for ways to further integrate some of its entry-level training.

The next step in that plan, for Marines, centers on boot camp. Mabus has ordered the service to plan to make its the service to is integrating women into their historically gender-segregated boot camp co-ed, but it's likely that the training will continue to be separate.  in January.

"He has been open to ask and answer questions others of a more conservative background would not," said retired Capt. Jerry Hendrix, a former naval flight officer, adding that he learned firsthand as an aviator during integration in the early 1990s that women are effective in combat.

"Mabus is sincerely interested in opening opportunities," he added. "And as a father of two daughters, I have to respect that."

On Wednesday: Has Mabus done enough to stop the shrinking size of the Navy's fleet?