Always a tough proposition on their own patch, Boro took an 18th minute lead through Yemi Odubade.
And it got even better for the hosts when Nathanial Pinney doubled their lead less than 2 minutes later after a lapse in concentration by the Iron defence.
But crucially, Scott Shulton reduced the deficit 8 minutes later and only a tremendous save by Boro`s Bailey Vose from Karl Oliyide prevented Braintree from going into half-time on level terms.
But just 3 minutes into the second period, Phil Roberts equalised and 4 minutes later, a near post finish from Billy Crook after another good save from Vose put the visitors in front for the first time.
And, despite some late pressure, Braintree held firm to open up with three valuable points.
Gloucester City, switched from the north to accommodate Leamington, were beaten 2-0 at Melbourne Stadium by fancied Chelmsford City.
A good opening day performance from the Clarets was rewarded with a brace from Kudos Oyenuga at either end of the game.
He put the hosts ahead after just 2 minutes when he latched onto a loose ball and fired home.
Then, with less than 3 minutes of normal time remaining, Oyenuga rose to power home a header to clinch victory.
League newcomers Chippenham Town and returnees Havant & Waterlooville met on the opening day at Hardenhuish Park.
And after neither side looked like breaking the deadlock, shared the spoils in a goalless draw.
Bognor Regis Town, who came up with Havant, enjoyed a 3-2 Nyewood Lane win over Bath City.
The Rocks raced into a two-goal lead, thanks to goals from Alex Parsons after 22 minutes and Jimmy Muitt just 5 minutes later.
City grabbed one back on the hour-mark when Nat Jarvis coolly finished from inside the area.
And they were level when last season’s top scorer Andy Watkins equalised with a powerful strike.
But Bognor claimed all three points when Ollie Pearce thumped a free-kick past new City keeper Luke Southwood.
Much-fancied Dartford were held to a 0-0 draw at Princes Park by Hungerford Town.
Joint-favourites for the title, the Darts were pretty toothless on the day against a determined Crusaders side.
Wealdstone opened up with a 2-1 win at Grosvenor Vale against Concord Rangers.
Elliot Benyon put the Stones in front on the quarter-hour mark.
Jordan Cox levelled for the Beachboys 2 minutes after the break, but they couldn’t hold on to the advantage as a goal from Dan Fitchett on the hour-mark won the points for the Stones.
St Albans City also started the new campaign off on a positive note, Ian Allinson`s side winning 3-2 at Marsh Farm against Oxford City.
It was the hosts who drew first blood after 24 minutes with a goal from Matt Patterson.
But right on half-time, the Saints pulled level through Shaun Lucien.
Seconds after the break, the visitors were in front when Solomon Sambou curled home a beauty.
A stunned Oxford side went further behind 6 minutes from time when Sam Merson fired in from the edge of the area.
Dave Pearce scrambled home a second for the home side in stoppage time, but there wasn`t time to find a leveller.
Hemel Hempstead Town also started the 2017/18 season off on a positive note by beating Whitehawk 3-0 at Vauxhall Road.
The Tudors took a 12th minute lead when Tom Hamblin met a far post cross, Hawks` keeper Alex Tozarcyk palmed his shot straight to Ben Greenhalgh who made no mistake from close range.
But it wasn`t until the 79th minute that Hemel made the game safe when Alex Osborn pounced after Tozarcyk had parried a Sam Hatton effort.
And they added a third a minute from time when Joe Howe fired home from 12 yards.
Poole Town began their new campaign with a 2-1 win at the Woodspring Stadium against Weston-super-Mare.
Just past the hour-mark and Weston took the lead – but it eventually did not count. In bizarre circumstances, Jake Reid bundled the ball home.
Celebrations ensued and Poole protested. After much deliberation, the referee changed his mind and disallowed the goal, and then booked Reid.
And it had an effect on Weston as `Gogglebox` star Tristan Plummer received two quick-fire bookings and left the Seagulls with ten-men.
And late signing Christian Oxlade-Chamberlain gave the visitors the lead with an excellent finish into the top corner.
Jake Smeeton then hammered home from a corner, before Reid ensured a nervy finale when he pulled one back.
Truro City were the day`s other winners, beating Welling United by the odd goal in five at Treyew Road.
Aaron Lamont gave the White Tigers an 11th minute lead that Cody Cooke doubled right on the stroke of half-time.
Player boss Jamie Coyle showed how it`s done by pulling the Wings back into the game on the hour-mark.
But River Allen popped up with Truro`s third in the 2nd minute of time added on.
East Thurrock United played out an entertaining 1-1 draw against Hampton & Richmond Borough at Rookery Hill.
A goal from debutant Montel Agyemang had handed Rocks a 52nd minute breakthrough.
However, Michael Kamara secured a point for the Beavers from the penalty spot 7 minutes later.
(Photo: St Albans City FC)